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ELEMENTARY 
AND  DENTAL 
RADIOGRAPHY 

BY 

HOWARD  RILEY  RAPER,  D.D.S. 

Professor    or    Roentgenology,    Operative    Tecnnic,  Materia 
Medica  ana  Therapeutics  at  the  Indiana  Dental  College, 
Indianapolis.      Past   Dental  Surgeon  to  the  Indiana 
School  tor  the  Feeble-Minded  Youth.     Mem- 
ber  Institute  or  Dental    Pedagogics,  local, 
etate    and    national    dental    societies. 
Associate   member    A.   M.   A., 
Section    or    Stomatology. 


WITH   354   ILLUSTRATIONS 

FIRST  EDITION 


Adopted  as  a  Text-Book  by  the  National  Association  of  Dental  Faculties 


NEW  YORK : 

Consolidated  Dental  Mfg,  Co. 

LONDON : 

Claudius  Ash.  Sons  &  Co.,  Ltd. 
1913 


' 


Copyright.  1913 

By  HOWARD  R.  RAPER 


Copyright.    191.3.    in   the  United    KinRdom 

By  CLAUDIUS  ASH.  SONS  &  CO..  LTD..  LONDON 


One   of  '  his   boys,    the  •writer, 

grasps  this  opportunity  to  show 

his  Jove  ana  respect  for 

GEORGE    EDWIN    HUNT, 
M.D.,  D.D.S. 

by  dedicating  this  book  to  him. 


Digitized  by  the  Internet  Archive 

in  2010  with  funding  from 
Columbia  University  Libraries 


http://www.archive.org/details/elementarydentalOOrape 


PREFACE. 

The  object  of  this  book  is  to  teach,  first,  the  elementary 
principles  of  radiography;  second,  special  dental  radiography. 

Tlic  first  part  of  the  book  is  written  on  the  presumption  that 
the  reader  knows  nothing  about  electricity,  photography,  or 
the  X-rays,  and  might  therefore  be  used  by  anyone  who  wishes 
to  take  up  radiographic  work,  whether  a  dentist  or  a  physician 
In  dealing  with  the  preliminary  subjects  mentioned,  an  earnest 
effort  has  been  made  to  avoid  useless,  impractical  and  confus- 
ing elaboration. 

The  second  part  of  the  book  is  devoted  to  dental  radiog- 
raphy, and  is  consequently  of  interest  mainly  to  dentists  and 
specialists  in  radiography  who  do  work  referred  to  them  by 
dentists.  It  gives  in  detail  the  special  technic  involved  in  the 
practice  of  dental  radiography,  also  a  chapter  with  one  hundred 
and  eighty-three  halftone  illustrations,  demonstrating  sixty- 
four  different  uses  to  which  the  radiograph  may  be  put  in  the 
practice  of  dentistry. 

The  use  of  the  radiograph  in  the  practice  of  modern  dentistry 
is  not  a  mere  fad;  it  is  a  necessity,  if  one  wishes  to  render  the 
best  dental  service.  Nothing  but  great  good  can  come  from  its 
more  frequent  use.  To  the  end  of  bringing  about  a  more 
extensive  use  of  the  radiograph  by  dentists  this  work  is  pub- 
lished. At  present  it  is  the  only  work  of  its  kind  on  the  book 
market. 

So  many  people  have  helped  me  in  the  compilation  of 
this  ■volume  that  I  refrain  from  naming  and  thanking  any 
particular  individual.  A  publication  of  this  kind,  of  necessity, 
represents  the  work  of  many. 

June  5,  1913.  H.  R.  R. 


CONTENTS 


CHAPTER  PAGE 

elementary  Radiography 

I.     Electricity T 

II.     X-Ray  Machines 14 

III.     X-Ray  Tubes  and  the  X-Rays 41 

!V.      Making  Radiographs 65 

Dental  Radiography 

V.     Making  Dental  Radiographs       .        .        .        .  •       .        .  85 

VI.     Reading  Radiographs 136 

VII.     The  Uses  of  the  Radiograph  in  Dentistry      .        .        .        .146 

VIII.     The  Dangers  of  the  X-Ray 273 

IX.     Purchasing  a  Radiograph  Outfit 292 

X.     Stereoscopic  Radiography 297 


elementary  and  Dental  Radiography. 

CHAPTER  I. 

electricity. 

Dental  radiography  is  the  science  and  art  of  making  pictures  of  the 
teeth  and  contiguous  parts  with  the  X-rays.  Its  place  and  value  in  the 
practice  of  modern  dentistry  will  be  dealt  with  later. 

Before  we  can  produce  X-rays  we  must  have  at  our  disposal  that 
something  called  electricity. 

Electricity  is  a  form  of  energy  closely  related 

Electricity.  to  motion,  light  and   heat.     We   know   it  is  closely 

related  to  motion,  light  and  heat  because  these  forms 
of  energy  can  be  made  to  produce  electricity,  and  electricity  conversely 
can  be  made  to  produce  them.  Electricity  is  discernible  to  but  one  of  the 
special  senses,  namely,  feeling.  It  cannot  be  seen,  heard,  smelled  or 
tasted.  Victims  of  severe  shocks  have  noted  a  peculiar  taste,  which  they 
call  the  taste  of  the  electricity,  but  it  is  my  opinion,  neither  proved  nor 
disproved  as  yet,  that  this  taste  is  due  to  the  presence  of  new  chemical 
bodies  formed  in  the  saliva  by  electrolysis.  In  other  words,  the  passage 
of  the  current  of  electricity  through  the  saliva  causes  chemical  changes 
to  occur,  resulting  in  the  formation  of  new  chemical  bodies,  and  it  is 
these  new  bodies,  not  the  electricity,  that  produce  a  taste. 

When  electricity  passes  from  one  place  to  an- 

Conductors.  other    the    substance    through    which    it    passes    is 

said  to  be  a  conductor.  A  substance  through  which 
electricity  passes  with  great  difficulty,  when  at  all,  is  said  to  be  a  non- 
conductor. Metals  are  the  best  conductors  of  electricity.  Silver  is  the 
best,  then  copper.  Copper  wire  is  the  most  used  of  any  conductor  of 
electricity.  German  silver  carries  electricity  very  reluctantly,  and  bis- 
muth is  the  poorest  conductor  of  the  metals.  It  was  formerly  thought 
that  electricity  traveled  on  the  surface  of  a  conductor,  but  if  this  were 
true  a  round  wire  could  be  made  to  carry  more  current  by  simply  flat- 
tening it  and  so  making  the  surface  greater:  while,  as  a  matter  of  fact, 


2  ELEMENTARY  RADIOGRAPHY 

the  flattened  wire  would  carry  less,  because  of  the  condensation  of  the 
metal  incident  to  flattening.  The  human  body  is  a  conductor.  Wood. 
glass  and  vulcanite  are  examples  of  non-conductors. 

\\  hen  electricity  passes  from  one  place  to  another  through  a  con- 
ductor, what   is  known  as  the  electric  current  is  established. 

There  are   four  kinds  of  electric  currents:    (i) 
Currents.  The  continuous,  constant,  or  direct  current,  commonly 

designated  D.C. ;   (2)    the  pulsating;   (3)    the  inter- 
rupted; 14)  the  alternating  or  oscillating,  designated  A.C. 

The  direct  current  is  one  in  which  the  electricity  is  presumed  to  flow 
through  the  conductor  in  one  direction  at  a  uniform  rate  of  pressure. 

The  pulsating  current  is  one  in  which  the  electricty  flows  through 
the  conductor  in  one  direction,  but  at  variable  pressure. 

The  interrupted  current  is  one  in  which  the  electricity  flows  through 
the  conductor  in  one  direction  while  in  motion,  but  which  is  completely 
arrested  in  its  flow  at  frequently  recurrent  intervals. 

The  alternating  current  is  one  in  which  the  electricity  Hows  through 
the  conductor  first  in  one  direction,  then  in  the  other.  When  the  current, 
tli. wing  in  a  given  direction,  reverses,  flows  in  the  opposite  direction,  and 
then  resumes  its  original  direction  of  flow,  it  is  said  to  have  completed  a 
cycle.  The  number  of  cycles  occurring  in  a  second  determines  the  fre- 
quency of  the  current.  We  thus  have,  for  example,  a  60-cycle  frequency 
current,  making  sixty  complete  alternations  per  second. 

Electricity  travels  from  one  place  to  another  be- 
Potcntial.  cause  of  a  difference  in  potential.     The  term  poten- 

tial means  latent,  inactive,  or  stored-up  energy. 
Take  lightning  as  an  example  of  traveling  electricity.  Why  does  it  occur? 
<  Ine  cloud  ha-  a  potential,  figuratively  speaking,  of  say  30,  another  of  20. 
These  cloud-  approach  close  enough  to  one  another  so  that  electricity 
can  jump  the  atmospheric  gap  between  them,  which  it  does,  passing  from 
the  one  with  a  potential  of  30  to  the  one  with  a  potential  of  20  and 
equalizing  the  potential  of  each  to  25.  The  lighl  of  lightning  is  caused 
b\  the  resistance  of  tin-  atmosphere  to  the  passage  ol  electricity.  If  such 
a  thing  were  possible  and  an  electric  conductor  stretched  from  the  one 
cloud  to  the  other,  the  potentials  would  be  equalized  as  just  described, 
but  without  the  occurrence  of  the  phenomenon  called  lightning,  because 
lectricity  would  unostentatiously  flow  through  the  conductor  instead 
of  through  the  highly  resistive  atmosphere. 

All  electricity-producing  machines    then,  simplv  create  a  compara- 
tively high  potential,  so  that   when  a  path   is  afforded—;,  e.,   when  con- 
ductor- are  attached  to  the  machine— the  electric'ty  leave-,  in  i'-  eft   it 
uali/e  pi  tential. 


ELECTRICITY  3 

Electricity  travels  at  an  inconceivably  rapid  rate 
UdOCity.  °f  speed,  instantaneous  results  being  obtained  hun- 

dreds of  miles  distant  on  pressure  of  a  button. 
It  is  stated  that  the  velocity  of  electricity  is  about  the  same  as  light,  which 
latter  travels  about  186,000  miles  per  second.  To  comprehend  this  great 
speed  compare  it  to  the  velocity  of  sound,  which  travels  only  1,090  feet 
per  second. 

In  dentistry  and  medicine  the  terms  used  can  often  be  translated 
literally  into  their  meaning.  For  example,  "odontalgia"  is  a  combination 
of  two  Greek  words  meaning  tooth  and  pain;  "tonsilectomy"  is  a  com- 
bination of  a  Latin  and  a  Greek  word  meaning  tonsil  and  excision.  Elec- 
trical terms  are.  however,  derived  principally  from  proper  names.  For 
example,  volt,  the  unit  of  measurement  of  electric  pressure,  has  no  literal 
meaning  at  all,  but  is  so  called  in  honor  of  Alexander  Yolta,  a  great  elec- 
trician.    And  so  with  the  terms  ohm,  watt  and  ampere. 

When    electricity    leaves    the    electricity-produc- 
UOlt.  ing,  or,  if  you  choose,  potential-creating,  machine,  it 

passes  into  the  conductors  at  a  given  pressure. 
This  pressure  is  measured  in  volts,  just  as  pressure  in  a  water-pipe  is 
measured  in  pounds.  The  volt,  then,  is  the  unit  of  measurement  of 
pressure  of  electricity.  Just  what  is  a  "unit  of  measurement"?  Take, 
for  example,  the  unit  of  linear  measurement;  it  is  called  the  "meter."  and 
and  is  one-ten-millionth  of  the  distance  from  the  equator  to  one  of  the 
earth's  poles.  The  unit  of  linear  measurement,  then,  the  meter,  is  a  definite 
name  applied  to  a  definite  distance.  So  the  volt  is  a  definite  name  applied 
to  a  definite  degree  of  electric  pressure,  or.  which  means  the  same  as 
electric  pressure,  electromotive  force,  designated  E.M.F.  This  force  is 
sufficient  to  maintain  a  current  of  electricity  of  one  ampere  ( the  unit  of 
measurement  of  volume  of  electricity)  through  a  resistance  of  one  ohm 
(the  unit  of  measurement  of  resistance  to  the  flow  of  current  offered  by 
an  electric  conductor).  Let  us  then  fix  this  firmly  in  our  minds.  The 
volt  is  the  unit  of  measurement  of  electromotive  force,  or  pressure. 
Though  it  is  not  commonly  used,  the  writer  much  prefers  the  word 
"pressure"  to  "force,"  believing  it  to  more  clearly  express  the  meaning. 

Xo   conductor  carries   electricity   without  ofifer- 
Obm.  ing  a  certain  amount  of  resistance  to  its  Mow.     This; 

resistance,  which  might  be  compared  to  the  friction 
offered  by  the  sides  of  a  pipe  to  the  flow  of  water,  is  measured  in  ohms. 
The  ohm.  then,  is  the  unit  of  measurement  of  resistance  offered  to  the 
flow  of  electricity  by  a  conductor,  and  is  equivalent  of  the  resistance 
afforded  by  a  column  of  mercury  having  a  cross-section  of  one  square 
millimeter  and  a  length  of  t  06.28  centimeters,  at  a  temperature  of  o°  C. 


4  ELEMENTARY  RADIOGRAPHY 

We   have   considered    pressure   and    resistance. 
flmpcrc.  Now  we  come  to  the  energy  itself,  which  may  be 

compared  to  the  water  in  a  water-pipe,  and  is  meas- 
ured in  amperes.  The  ampere  capacity  of  an  electric  conductor  cor- 
responds to  the  cross-section  of  a  water-pipe,  which  latter  is  measured  in 
square  inches.  Thus  the  larger  the  pipe,  which  means,  of  course,  more 
square  inches  in  its  cross-section,  the  more  water  it  will  carry ;  and  so 
the  larger  the  electric  conductor  of  a  given  material  the  greater  its  ampere 
capacity,  and  the  more  electricity  it  will  carry. 


d^L 


FIG. 


The  analogy  between  the  water  in  the  water-pipe  and  the  electricity 
in  the  conductor  is  not  perfect,  however.  A  given-sized  pipe  will  carry  a 
column  of  water  of  a  given  cross-section  and  no  more,  because  water  is 
practicallv  non-compressive.  When  the  flow  of  the  water  is  opposed  to 
gravity,  as  when  drawing  water  from  a  faucet,  this  complete  cross-sec- 
tion must  be  obtained,  too — that  is,  the  pipe  must  be  full — before  any 
pressure  will  establish  a  current  through  the  pipe.  Not  so  with  electricity 
in  a  conductor.  A  wire  which  has  a  normal  capacity  of  say  30  amperes 
will  carry  a  current  of  10,  and  it  can  be  made  to  carry  40  or  50  by  in- 
creasing the  pressure,  because  electricity  is  compressible. 

Amperage,  or  the  volume  of  electricity  carried  in  a  conductor,  de- 
pends  "ii  two  things — the  pressure  of  the  current  and  the  resistance  of 
the  conductor.  Hence  Ohm's  law,  which  is  that  the  volume  of  the  current 
can  be  obtained  by  dividing  the  pressure  by  the  resistance.  In  other 
words,  the  amperage  can  be  obtained  by  dividing  the  volts  by  the  ohms. 

Problem:  An  electromotive  pressure  of  100  volts  is  acting  against 
a  resistance  of  50  ohms.  What  is  the  ampere  strength  of  the  current? 
ilution:     100  volts  divided  by  50  ohms  equals  2  amperes. 

To  give  the  exact  amount  of  electricity  represented  by  the  ampere, 
it  i-  that  amount  which,  when  passed  through  a  standard  solution  of  sil- 
ver nitrate  in  distilled  water,  will  cause  a  deposition  of  metallic  silver  at 
the  r;it<-  of  i.uS  milligrams  per  second. 


ELECTRICITY 


Electromotive    power    (not   electromotive   pres- 

Ulatt.  sure  or  force;  note  the  word  "power"),  or  the  ability 

of  a  current  to  do  work,  depends  on  two  things — 

the  pressure  measured   in  volts  and  the  volume  measured   in   amperes. 

This  is  also  true  in  hydraulics.     The  amount  of  work  a  stream  of  water 

will  do  depends  on  pressure  and  volume.     The  watt  is  the  unit  of  meas- 


Fig. 


Fig.   :;. 


Fig.    2.     Arrows   A    represent   the   direction   of  flow   of   electric   current.      Arrows   B    represent   the 

direction    of    flow    of    magnetic    flux    in    the    magnet. 

Fig.    3.     Bar    magnet    with    polarity    indicated. 

urement  of  electromotive  power,  and  the  wattage  of  a  current  is  obtained 
by  multiplying  the  volts  by  the  amperes.  Thus,  if  we  had  a  current  of  one 
ampere  under  a  pressure  of  one  volt,  one  watt  would  be  operative. 

When  i.ooo  watts  are  active  for  an  hour — that  is,  when  a  current 
i,ooo  watts  strong  has  been  in  motion,  the  current  turned  on,  for  one 
hour — the  electrometer  will  register  one  kilowatt-hour.  So  bills  for  elec- 
tricity are  made  out  for  so  many  kilowatt-hours. 

Magnetism    is    a    form    of   kinetic    energy   very 

magnetism.  closely    related    in    its    nature    to    electricity.      Mag- 

netism produces  electricity,  and  vice  versa. 


6  ELEMENTARY  RADIOGRAPHY 

The  substance  in  which  this  energy,  or  property,  magnetism,  resides 
is  called  a  magnet. 

1  f  a  bar  of  magnetized  steel  be  dropped  into  iron  filings,  and  then 
raised,  the  fillings  will  adhere  to  the  ends  of  the  bar,  but  not  to  the  center. 
(Fig.  i.) 

The  ends  of  the  bar  represent,  respectively,  the  north,  or  positive, 
and  the  south,  or  negative,  poles  of  the  magnet.  If,  now,  this  bar  be 
broken  at  its  exact  center,  instead  of  having  a  half  magnet  all  north 
pole  and  another  half  magnet  all  south  pole,  we  have  two  magnets  with 
two  poles  each.  If  one  of  these  magnets  be  broken  at  its  center  the  same 
thine  occurs,  namelv,  two  magnets,  each  one-half  as  large  as  the  first, 


Fig.    i.     When   poles  are  arranged  as   in  A   repulsion   exist-  between   the  magnets.     When   poles 

an-    arranged    as    in    I',    the    magnets   are    attracted    t<>    one    another    with    the    magnetic    flux    <>f 

each   north  pole   flowing  into  the  south   pole   of  the  other  magnet. 


are  made.-.     This  redivision  can  he  repeated  down  to  the  molecule,  which 

would   have  a  north  and   a  SOUth   pole. 

Magnets  are  of  two  kinds — the  natural  magnet,  or  "loadstone,"  and 
the  artificial  magnet-. 

'[lie  earth  may  he  considered  a  large  magnet,  the  poles  of  this  mag- 
net being  near  the  north  and  south  poles  of  the  earth.  The  natural  mag- 
net is  iron  ore,  found  in  nature  with  all  the  properties  of  the  magnet,  and 
representing  a  portion  of  the  great   magnet,  the  earth. 

Artificial  magnets  are  of  four  kinds— the  electro-magnet,  the  perma- 
nent magnet   and  the  induced  magnet. 


ELECTR1CI1  Y 


If  a  bar  of  soft  iron  be  wrapped  with  insulated  wire  (wire  covered 
with  a  nonconductor)  and  a  current  of  electricity  b"e  sent  through  the 
wire,  the  iron  bar  becomes  magnetized  while  the  current  passes  through 
the  conductor,  but  loses  its  magnetism  when  the  current  ceases  to  flow. 
Such  a  magnet  is  called  an  electro-magnet.  (Fig.  2.)  If  the  current  be 
sent  through  the  conductor  in  the  opposite  direction  to  that  shown  in  the 
diagram,  polarity  of  the  magnet  will  be  changed:  the  north  pole  will 
become  the  south  pole  and  the  south  pole  the  north  pole. 


Fig.   5. 


Fig.   6. 


If  hard  steel,  instead  of  soft  iron,  be  used  as  the  core  and  wrapped 
with  insulated  wire  and  a  current  of  electricity  be  sent  through  the  wire 
for  a  great  length  of  time,  then  the  current  shut  off  and  the  wire  removed, 
it  will  be  found  that  the  steel  retains  its  magnetism  and  will  continue  to 
retain  it  over  a  number  of  years.  Such  a  magnet  is  called  a  permanent 
magnet  (  Figs.  1  and  4,  for  example ) ,  though  it  is  not  actually  permanent 
and  will  lose  its  magnetism  in  time.  The  permanent  magnet  in  greatest 
general  use  is  the  "horseshoe"  magnet  (Figs  4  and  5),  which  is  simply 
the  bar  magnet  (Figs.  1  and  3)  bent  into  horseshoe  or  staple  shape. 

Instead  of  using  the  electric  current,  a  permanent  magnet  can  be 
made  by  rubbing  hard  steel  with  another  magnet. 

Fig.  3  shows  a  magnet  holding  three  nails.     As  long  as  the  magnet 


8 


ELEMENTARY   RADIOGRAPHY 


remains  in  contact  with  the  first  nail  it  will  hold  the  second  nail,  and  the 
second  will  hold  the  third.  But  remove  the  magnet  and  no  attraction 
exists  between  the  nails.  While  the  magnet  touches  the  first  nail  each 
nail  is  an  induced  magnet,  with  a  north  and  south  pole,  as  shown  in  the 
figure. 

While  either  the  north  or  south  pole  of  a  magnet  will  attract  a  piece 
of  unmagnetized  iron  or  steel,  only  unlike  poles  of  two  magnets  will  be 
attracted  to  one  another.  Thus,  if  two  north  or  two  south  poles  of  mag- 
nets he  brought  in  close  proximity  repulsion  instead  of  attraction  exists 
between  them      (  Fie.  4. ) 


Fig.    7.     Magneto-Dynamo.      A.    the    magnets    or    field.       B,    casting    surrounding    revolving    con- 
ductor or  armature.     <'.   appliance   for  outlet    "t'  electricity    from   armature.      An   alternating  cur- 
rent   i-   generated    bj    this   machine. 


In  183]  Faraday  discovered  that  when  an  electric  conductor  is  set 
in  motion  so  as  to  cut  the  lines  of  force  of  the  magnet  at  right  angles,  an 
electric  current  is  induced  in  the  conductor. 

Fig.  5  shows  the  lines  of  force  of  a  horseshoe  magnet  passing  from 
the  north  to  the  south  pole.  Imagine  now  a  spool  wrapped  with  copper 
wire,  not  as  thread  is  wound  around  a  spool,  but  lengthwise  oi  the  spool, 
the  wire  passing  over  it-  end-.  Place  this  spool  between  the  poles  of  the 
magnet,  revoke  it  on  its  axis,  and  the  copper  wire— that  is,  the  electric 
conductor — is  made  to  cut  the  force  of  the  magnet  at  right  angles  and  an 
alternating  current  of  electricity  will  be  produced  in  the  wire  (Fig.  6), 
the  current  flowing  in  opposite  directions  as  the  different  poles  are  passed. 


ELECTRICITY  9 

Add  to  this  arrangement  a  means  for  carrying  the  current  away  from  the 
apparatus  and  we  have  the  magneto-dynamo,  now  very  extensively  used 
in  automobiles.     (Fig.  7.) 

Dynamos  may  be  divided  into  two  classes :  the 
Dynamos.  magneto-dynamo,    just    described,    and    the    electro- 

dvnamo. 


Fig.    8.     A    Direct    Current    Generator    or    Electro-Dynamc 


All  dynamos  consist  of  three  cardinal  parts,  to  wit :  the  field,  or  mag- 
nets;  the  armature,  or  revolving  conductor,  and  the  rings,  or  appliance 
for  carrying  off  the  electricity.  If  the  current  sent  out  is  direct  instead 
of  alternating,  a  commutator  instead  of  rings  must  be  used.  A  commu- 
tator is  an  appliance  which  changes  the  alternating  current  induced  in 
the  armature  into  a  direct  current  as  it  leaves  the  dynamo. 

The  electro-dynamo,  an  example  of  which  is  shown  in  Fig.  8,  dif- 
fers in  principle  from  the  magneto-dynamo  only  in  the  kind  of  magnets 
used.  Permanent  magnets  are  used  in  the  magneto-dynamo  whereas 
electro-magnets  are  used  in  the  electro-dynamo. 

Immense  electro-dynamos,  or  generators,  as  they  are  called,  make 


io 


ELEMENTARY  RADIOGRAPHY 


our  commercial  currents,  steam  power  being  used  to  revolve  their  arma- 
tures. By  commercial  current  is  meant  the  electric  current  supplied  to 
us  by  the  electric  light  and  power  companies. 

Let  us  trace  a  current  of  electricity  through  what  is  known  as  the 
electric   circuit.     When   the   armature   is  revolved  the  potential   at  C,  of 


Six   Pole   Direct   Current   Generator,  parts  disassembled.      E,   electro-magnets   with   poles 
of   differenl    denominations   directly    opposite    one   another  -the    field.      Large    alternating   current 
tors     have     as     many     as     10    poles     in     the     field     which     revolves,     the     armature     remaining 
ionary.      A.   armature.      (',    commutator. 


Fig.  7.  rises.  The  potential  of  the  positive  wire  attached  to  binding  post 
—  (which  post  is  connected  to  C)  is  instantly  raised  to  thai  of  C,  and 
the  current  ceases  to  flow,  potential  being  equalized  between  the  arma- 
ture and  tbe  positive  wire.  If  now  the  positive  wire  ot  the  high  poten- 
tial be  brought  in  contact  with  the  negative  wire,  which  is  of  low  poten- 
tial the  current  flow-  into  the  latter.  Tbe  negative  wire  is  attached  to 
the  negative  binding  post,  which  is  connected  to  the  magnets  themselves. 
Thus  tb«-  current   passes  through  the  negative   wire  into  the  magnets. 

which  have  a  low  potential.  Tbe  current  will  continue  to  flow,  making 
a  circuit  from  C,  out  through  the  positive  wire,  back  through  the  nega- 
tive wire,  into  the  magnet^  until   their   (the  magnets')   potential   is  raised 


ELECTRICITY 


i  r 


to  that  of  C.     If  an  incandescent  light  bulb  be  connected  to  the  positive 

and  negative  wires  the  current  will  pass  from  the  positive  wire,  through 
the  bulb,  and  into  the  negative  wire.  As  the  electricity  passes  through 
the  bulb  it  heats  the  filament  of  carbon  to  incandescence,  producing  light 
and  some  heat.  Most  of  the  electricity  is  used  up  in  the  production  of 
the  light  and  heat — this  is  true  if  the  circuit  is  what  is  called  "well  bal- 
anced"— but  what  is  not,  travels  in  the  negative  wire  toward  the  magnet, 
equalizing  potential  until  it  dissipates  itself  in  the  effort. 


C- 


Fig.    10.      Diagram    of    a    step-down    transformer. 


Commercial  circuits  supply  either  a  D.C.  (direct  current)  or  an  A.C. 
(  alternating  current ) .  The  wiring  from  the  D.C.  dynamo  to  the  consumer 
is  an  intricate  problem,  difficult  to  understand.  It  is  enough  for  us  to 
know  that  the  D.C.  is  supplied,  as  a  rule,  only  to  downtown  districts  of 
cities,  by  a  circuit  giving  no  volts  pressure,  or  a  special  three-wire  cir- 
cuit, which  supplies  either  no  or  220  volts,  according  to  the  manner  of 
the  connections  made  to  the  mains.  The  amperage  depends  on  the  size 
of  the  wires  ;  the  more  amperage  desired  the  larger  the  wires  connecting 
to  the  mains  must  be. 

The  A.C.  leaves  the  generator  at  a  voltage  of  from  1,000  to  3,000  and 
flows  in  the  mains  at  this  pressure.  Such  great  pressure  is  both  danger- 
ous and  uselessly  high  for  ordinary  uses,  such  as  lighting,  running  motors, 
operating  X-ray  machines  and  the  like.  So,  by  means  of  a  transformer, 
the  voltage  is  reduced  to  any  desired  strength,  usually  from  100  to  125 
volts.     The  commercial  A.C.  is  either  60  or  133-cycle.  usually  60. 

Since  the  principle  involved  in  the  transformer  is  quite  similar  to 
the  one  met  with  in  X-ray  machines  a  description  of  it  would  not  be  out 
of  place  in  this  work.  Fig.  10  shows  the  plan  of  construction  of  a 
transformer.  A  represents  an  iron  core,  around  which  is  wrapped  insu- 
lated wire.  This  is  the  primary  winding  through  which  passes  the  pri- 
mary current  at  the  high  voltage  of  from  1.000  to  3,000.  As  always,  the 
amperage  depends  on  the  size  of  the  wire.     B  represents  another  iron 


12 


ELEMEXTARY  RADIOGRAPHY 


core,  around  which  is  also  wrapped  insulated  wire.  This  is  the  secondary 
winding,  through  which  the  secondary  current  passes.  "C  shows  soft 
iron  connections  between  the  two  cores. 

When  the  electric  current  is  established  in  the  primary  winding  a 
current  is  set  up  or  induced  in  the  secondary  winding.  Bear  in  mind 
there  is  no  electric  connection  between  primary  and  secondary  windings. 


Fig.    II.     A    Transformer. 


The  primary  current  enter-,  and  leaves  unaltered  except  for  a  slight  loss 
in  amperage,  but  in  its  passage  it  induces  a  current  in  the  secondary. 

If  the  wire  used  in  the  secondary  winding  be  of  the  same  length  and 
size  as  that  used  in  the  primary  winding,  the  induced  secondary  current 
will  be  of  practically  the  same  voltage  and  amperage  as  the  primary  cur- 
rent. But  if  the  wir.-  in  the  secondary  be  shorter  and  larger,  the  induced 
current  will  be  lower  in  voltage  and  higher  in  amperage.  <  >r  it  the 
wire  of  the  secondary  winding  be  longer  and  smaller  than  the  wire  in 
the  primary  winding,  the  induced  secondary  current  will  be  higher  in 
voltage  and  lower  in  amperage  than  the  primary  current.  The  wattages 
of  the  primary  and  secondary  currents  remain  practically  the  same.  For 
example,  suppose  the  voltage  of  the  primary  current  is  [,000,  the  am- 
perage  5.  the   wattage   would   be   5.000.      Suppose  now.  by   means  of  the 


ELECTRICITY 


13 


transformer,  the  voltage  is  lowered  to  100;  there  would  he  a  raise  in  am- 
perage to  50.  Notice  the  wattage  remains  the  same,  5,000.  The  figures 
do  not  represent  what  actually  happens,  since  they  do  not  take  into  ac- 
count the  loss  of  current  due  to  the  internal  or  intrinsic  resistance  of  the 
transformer,  hut  they  do  represent  roughly  the  general  principle  of  the 
action  of  the  transformer. 

A  transformer  which  lowers  voltage — the  kind  used  on  A.C.  cir- 
cuits between  mains  and  consumer — is  known  as  step-down  transformer; 
one  which  raises  voltage  is  a  step-up  transformer. 

The  transformer  does  not  alter  the  nature  of  the  current.  That  is, 
the  secondary  is  an  alternating  current,  the  same  as  the  primary,  the 
change  being  only  in  voltage  and  amperage.  Transformers  cannot  be 
used  on  a  direct  current. 

The  foregoing  is  calculated  to  give  the  reader  a  speaking  acquaint- 
ance with  electricity,  the  wonderful  force  which  produces  X-rays.  Fur- 
ther treatises  of  the  subject  will  be  made  as  necessity  demands.  It  will 
be  noted  that  but  one  source  of  electricity  has  been  considered,  namely, 
dynamo  electricity — that  furnished  by  light  and  power  companies.  Be  it 
known,  however,  that  electricity  can  be  produced  by  means  other  than  the 
dynamo — by  friction  and  chemical  change,  for  examples.  We  have  con- 
sidered only  the  source  of  electricity  which  is  used  to  operate  the  X-ray 
coils. 


CHAPTER  IT. 

X-Ray  machines. 

It  was  stated  in  Chapter  I  that  an  electric  current  is  necessary  to 
produce  X-rays,  but  nothing  was  said  concerning  the  strength  of  the 
current  required.  It  takes  a  current  very  high  in  voltage,  varying  from 
30.000  to  300,000  or  more  volts,  and  low  in  amperage,  the  amperage 
being  measured  in  milliamperes. 

The  ordinary  commercial  circuit  for  lighting  purposes  is  almost  in- 
variably either  D.C..  1  10  volts,  or  A.C.,  60-cycle,  100  to  125  volts.  The 
amperage  varies  according  to  the  amount  of  electromotive  power  needed, 
ranging  from  4  to  5  to  over  100  amperes.  The  commercial  current,  as 
supplied,  is  therefore  useless.  However  it  will  operate  a  machine  which 
will  give  the  desired  current. 

X-ray  machines  are  of  two  classes:    Those  that 
X.Ray  generate   their  own   electricity   without   any   external 

machines.  electric  supply,  and  those  that  depend  on  a  commer- 

cial current  or  storage  batteries  to  excite  them. 
There  i>  but  one  of  the  first  class,  namely,  the  static  machine  (  Fig.  12). 
and  of  the  second  class  there  are  three — the  Ruhmkorff  coil  (  Fig.  13), 
the  high  frequency  or  Tesla  coil  I  Fig.  14).  and  the  "interrupterless"  coil 
I  Fig.  [5).  All  of  the  latter  class  are  literally  induction  coils,  just  as  the 
transformer,  described  in  Chapter  I  is  an  induction  coil,  but  when  the 
term  induction  coil  is  used  we  may  assume  that  it  is  the  Ruhmkorff  coil 
that  is  referred  to.  We  shall  follow  the  precedent  and  call  the  Ruhm- 
korff coil  the  induction  coil,  though  it  is  no  more  an  induction  coil  than 
the  high-frequency  or  "interrupterless"  coils. 

The  static  machine  is  so  much  inferior  to  the  induction  coil  for  pic- 
ture work,  and  so  large  and  difficull  to  Operate,  compared  with  any  coil, 
thai  the  only  reas<  n  for  using  it  would  be  the  lack  of  a  commercial  cur- 
rent with  which  to  operate  a  coil.  Even  in  such  an  event—  the  lack  of  a 
commercial  current — I  would  advise  the  use  ol  an  induction  coil  operated 
by  storage  batteries  I  Fig.  16)  in  preference  to  the  static  machine 

14 


X-RAY  MACHINES 


*5 


The    induction    coil    is    the    most    popular    ap- 
TlldUCtion  paratus    for    giving    the    electric    current    necessary 

€oil.  for    X-ray    picture    work.       It    is    a    step-up    trans- 

former to  this  extent,  namely,  its  primary  current  is 
of  comparatively  low  voltage  and  high  amperage,  while  the  secondary  is 
very  high  in  voltage  and  low  in  amperage.  It  differs  from  the  trans- 
former in  mechanical  construction,  and  also  in  that  the  primary  current 
must  be  an   interrupted   current    and   the   secondary,   induced   current   is 


Fig.     12.      A    static    machine. 


practically  a  uni-directional  one.     It  will  be  recalled  that  the  primary  and 
secondary  currents  of  the  transformer  are  both  alternating. 

Let  us  trace  a   current   of   electricity    from   the 
Installation.  mains  through  an  induction  coil  and  auxiliary  appli- 

ance leading  to  it.     (Fig.   17.) 
Wiring  from  the  mains  to  the  coil  should  always  he  done  by  a  com- 
petent electrician.     A  wire  of  a  given  size  will  carry  only  a  certain  am- 
perage without  heating.     If  this  amperage  be  exceeded  greatly  the  wire 


i6 


ELEMENTARY  RADIOGRAPHY 


may  become  hot  enough  to  set  fire  to  surrounding  building  material  of  a 
combustible  nature.  There  are,  therefore,  laws  governing  the  size  of 
wires  to  be  used  to  carry  different  amperages.  Coils  are  rated  by  their 
manufacturers   to   consume   a   certain   number   of   amperes,    and    wiring 


Fig.    13.     Induction  or    Ruhmkorfl  coil. 


should  be  done  according  to  this  rating.  The  amount  of  amperage  neces- 
•  to  operate  a  coil  varies  directly  according  to  the  size  of  the  coil — 
the  larger  the  coil  the  more  amperes  it  takes.  Assuming  tin-  coil  to  be 
of  a  medium  large  size,  the  lead  wires  used  to  conned  it  t<>  the  mains 
should  be  capable  of  carrying  at  least  30  amperes  without  heating!  B) 
"lead  wire>"  I  mean  the  win-  leading  to  the  machine — not  lead  (the 
metal )  wires.     The  wires  arc  copper. 


X-RAY  MACHINES  17 

Somewhere    near    where    the    wires    enter    the 
fuses.  building,  and  also  at  the  coil  itself,  will  be   found 

fuses.  (Fig.  18.)  A  fuse  is  a  wire,  an  alloy  of 
lead,  of  a  given  size,  and  fusing  point  capable  of  carrying  only  a  limited 
amperage  without  melting.  Thus  if  more  than  30  amperes  be  sent 
through  a  30-ampere  fuse,  the  wire  is  heated  to  its  fusing  point,  it  melts, 
the  circuit  is  broken,  and  the  flow  of  electricity  is  stopped.     A  fuse  is  a 


Fig.    14.      High-frequency    coil. 


sort  of  safety  valve.  About  30  ampere  fuses  should  be  used  for  a  medium 
large  induction  coil.  This  information,  however,  will  always  be  given 
by  the  manufacturers  of  the  coil. 

Somewhere  near  where  the  wires  enter  the  build- 
SwitChCS.  ing,   and  also  at  the  coil,  are  placed  switches.     An 

electric  switch  (Fig.  19)  is  an  appliance  for  throw- 
ing the  electric  current  into,  and  out,  of  an  extended  or  auxiliary  circuit. 

Assuming  that  the  current  at  our  disposal  is  D.C..  it  must  first  be 
passed  through  an  interrupter. 

An  interrupter  is  an  electric  apparatus  by  means 
Interrupters.  of  which  a  constant  current  is  converted  into  an  in- 

terrupted one.  Interrupters  are  of  three  kinds  :  ( 1 ) 
The  electrolytic.  Fig.  20;  (2)  the  mercury  turbine.  Fig.  21,  and  (3)  the 
mechanical  or  vibrator.  Fig.  22. 

For  picture  work,  in  connection  with  the  induction  coil,  the  elec- 
trolytic, or,  as  it  is  sometimes  called  in  honor  of  the  inventor,  the  YVeh- 
nelt  interrupter,  is  quite  the  best.     With  it  the  constant  current  may  be 


<r 


18 


ELEMENTARY  RADIOGRAPHY 


interrupted  at  the  rate  of  from  60  to  30000  interruptions  per  minute. 
The  mercury  turbine  gives  from  200  to  3,600  interruptions  per  minute. 
and  the  vibrator  from  250  to  1,000  interruptions  a  minute. 


Fig.    15.     Interrupterless   coil. 


The  electrolytic  interrupter  consists  of  a  glass  jar  containing  a  solu- 
tion of  sulphuric  acid  in  water,  the  electrolyte,  in  which  is  immersed  a 
platinum  point  electrode,  A  (Fig.  20),  and  a  lead  electrode;  l'>.  The 
platinum  is  covered  with  a  porcelain  sheath,  C  except  for  its  point,  which 
projects  into  the  electrolyte.    Little  or  much  of  the  poinl  may  be  exposed 

in  the  acid   by  the  regulating  arm,   I). 

\\  «•  have  two   wires  now   leading   from   the   mains  to  our  apparatus. 


X-RAY  MACHINES 


19 


(  >f  these  one  is  the  positive  wire  which  brings  the  electric  current,  and 
the  other  is  the  negative  or  return  wire.  The  positive  wire  must  be  at- 
tached to  the  binding  post  of  the  platinum  electrode,  marked  -f-.     (Fig 


Fig.    10.      Induction    coil    for    use    with    storage    cells. 


20.)  But  how  can  we  tell  which  is  the  positive  wire?  Cut  some  of  the 
insulation  off  the  ends  of  the  wires,  immerse  them  in  a  glass  of  water, 
and  bubbles  will  be  given  off  from  the  negative  wire.  When  making 
this  test,  care  should  be  taken  not  to  touch  one  wire  to  the  other,  so 
making  a  short  circuit.  The  term  (short  circuit)  almost  explains  itself. 
The  desired  circuit  in  this  instance  is  from  the  positive  wire,  through  the 
water,  which  is  highly  resistive  to  the  flow  of  electricity,  into  the  negative 
wire  and  back  to  the  mains.     Suppose  that  the  wires  come  in  contact 


20 


ELEMENTARY  RADIOGRAPHY 


(that  portion  of  the  wires  from  which  the  insulation  has  been  removed), 
the  current  no  longer  passes  through  the  water,  but  takes  the  shorter 
path  of  less  resistance,  passing  directly  from  positive  to  negative  wire. 
All  the  amperage  formerly  used  and  choked  back  by  the  resistive  water 
flows  through  the  wires,  heating  them  rapidly. 


Fuses 
Switch 


Shdin$  Rods  io 

regulate  length  Of 

spark  gap 


■Secondary  K 
Terminals 


Interrupter 


Rheostat 


Fijy.  11 


Coil 


The  course  of  the  electric  current,  through  the  electrolytic  inter- 
rupter. i->  from  platinum  through  the  acid  electrolyte,  and  on  through 
the  lead  electrode.  As  the  current  flows  through  the  acid  solution,  a 
chemical  change  occurs  and  a  gas  is  formed.  This  gas  accumulates  in 
the  form  of  a  bubble  around  the  exposed  platinum  point,  and  momentarily 
stops  the  flow  of  the  current.    Then  the  bubble  bursts  and  the  current  is 

tablished  onl)  to  be  stopped  again  in  the  manner  just  described,  and 
so  on.  The  more  platinum  exposed  in  the  solution  the  slower  the  inter- 
ruptions and  the  more  amperage  will  pass  through  the  interrupter.  In 
order  that  the  amperage  may  be  increased  without  producing  a  corre- 
sponding decrease  in  the  number  of  interruptions  per  minute,  interrupters 
arc  made  with  several  platinum  points.  I  Fig.  23.  )  Thus  with  a  multi- 
point interrupter,  when  more  amperage  is  desired,  more  points  are  thrown 
into  tin-  circuil  by  means  of  small  switches  for  the  purpose.    A  two-point 


X-RAY  MACHINES 


21 


interrupter  will  draw   enough  amperage,  and  give  sufficiently  rapid  in- 
terruptions, for  dental  radiographic  work. 

The  current  is  sometimes  stopped  altogether  by  the  interrupter.  This 
may  be  due  to  the  accumulation  of  a  large  bubble  of  gas,  on  the  platinum 
point,  which  will  not  burst.     By  moving  the  point — or  points  if  the  inter- 


Fig.    IS.     Patent    fuses    or    cutouts. 


rupter  is  multipointed — up  and  down  several  times  by  means  of  lever  D, 
Fig.  20,  the  bubble  will  be  broken  and  the  current  re-established. 

On  a  D.C..  no-volt  circuit  the  electrolyte  should  be  15  to  20  per 
cent,  acid;  on  a  D.C..  220-volt  circuit,  from  5  to  8  per  cent,  is  strong 
enough.  The  jar  should  be  one-half  or  three-quarters  full.  As  the  solu- 
tion stands,  some  of  the  water  evaporates,  so  raising  the  per  cent,  of  acid 
in  tbe  electrolyte.  As  this  occurs,  more  water  should  be  added.  The 
strength  of  the  solution  can  be  easily  and  accurately  determined  by  means 
of  a  special  hydrometer.  (Fig.  24.)  As  the  water  evaporates,  and  the 
solution  gets  stronger,  its  specific  gravity  raises.  The  hydrometer  is 
sensitive  to  this  change  of  specific  gravity,  and  shows  by  a  special  marking 
the  exact  per  cent,  of  the  solution. 

As  the  current  passes  through  the  interrupter,  heat  is  produced. 
Hence  the  glass  jar  is  placed  in  a  metal-lined  box  and  the  box  filled  with 
water.  (Fig.  23.)  Even  with  this  means  for  cooling,  when  used  con- 
tinuously for  fifteen  minutes  or  longer,  the  electrolyte  becomes  so  heated 
that  the  interrupter  no  longer  works  properly.  In  dental  picture  work., 
though,  the  time  of  operation  is  a  matter  of  seconds.  Tt.  therefore,  will 
be  understood  that  no  trouble  ever  occurs  due  to  heating  of  the  elec- 
trolvte. 


22 


ELEMENTARY  RADIOGRAPHY 


u 


i* 


Diagrammatic  illustration  showing  ihi  an  electric  switch.    The  single 

.it  we  shall  call   (not  knowing  :i  bettei    name)   the  original 

The  double  arrows  mark  an  extended  circuit.     The  drawing  shows  the  switch 

if   the   double   1-  >  closed.     With   the   ^wi  tcli   open   the  current    could 

no)   i  ;t-s  through  the  extended  circuit 


X-RAY  MACHINES 


23 


When  the  X-rays  are  used  for  their  therapeutic  value,  long  ex- 
posures are  made;  so  long  that  undue  heating  of  the  electrolytic  inter- 
rupter would  be  sure  to  occur.  Hence,  for  this  work  the  mercury  turbine 
interrupter  (Fig.  21)  is  best.  In  principle  the  mercury  turbine  is  a 
mechanical  interrupter,  depending  on  no  chemical  change  for  its  action, 
being  operated  by  means  of  a.i  electric  motor.     We  shall  not  consider  it 


Fig.   ^n.     Non-water  cooled   one-point   electrolytic   interrupter. 


further,  for  it  should  not  be  used  for  picture  work,  except  in  the  absence 
of  an  electrolytic  interrupter. 

The  mechanical  interrupter,  or  vibrator  (Fig.  22),  is  used  only  on 
the  smallest  coils.  The  principle  on  which  it  operates  is  the  one  involved 
in  the  construction  of  electric  bells ;  Fig.  25  illustrates  the  principle.  A  is 
a  movable  arm  with  fulcrum  at  B.  When  the  current  travels,  the  path 
marked  with  arrows,  the  electro-magnet,  C.  draws  the  movable  arm  A, 
over  to  it,  breaking  the  circuit  at  D.  When  the  circuit  is  broken  the 
electro-magnet  loses  its  magnetism  and  the  spring,  E.  draws  the  movable 
arm  back,  re-establishing  the  circuit.  The  rapidity  of  interruptions  may 
be  regulated  by  altering  the  strength  of  the  spring.  A  popular  form  of 
vibrator  is  the  ribbon  vibrator  illustrated  in  Fig.  26. 


24 


ELEMENTARY  RADIOGRAPHY 


In  tracing  the  current  directly  from  the  supply 

Rectifier.  wire  into  the  interrupter,  we  have  assumed,  as  stated, 

that  we  are  receiving  our  supply  from  a  D.C.  circuit 

Suppose    however,  that  the  only  current  at  our  disposal  is  A.C.,  as  is 

often  the  case.     It  is  necessary  to  send  the  alternating  current  through  a 

rectifier  |  Fig.  2~  I   before  allowing  it  to  enter  the  interrupter. 

A  rectifier  is  an  electrical   apparatus  by  means  of   which  an  alter- 
nating current  is  converted  into  a  uni-directional.  pulsating  current,  and 


Fig.    21.     Mercury    turbine    interrupter. 


consists  of  a  glass  jar  containing  an  electrolyte,  a  solution  of  ammonium 
phosphate  usually,  in  which  is  immersed  a  steel  electrode  and  an  alumi- 
num electrode.  The  jar,  the  electrolyte  and  the  two  electrodes  consti- 
tute one  cell.     Fig.  27  shows  a  one-cell  rectifier. 

With  the  direct  current,  we  are  able  to  test  and  determine  which 
of  the  two  lead  wires  is  positive.  This  is  impossible  with  the  alternating 
current,  because  polarity  changes  at  each  alternation.  Either  of  the  lead 
wires  ma\  therefore  In-  attached  to  the  steel  electrode,  and  a  wire  con- 
nected from  the  aluminum  electrode  to  the  platinum  of  the  interrupter. 
A-  long  as  tin-  aluminum  remains  the  negative  electrode  of  the  rectifier, 
the  current  flows  in  m  steel  to  aluminum  and  on,  but  when  the  current 
and  starts  to  flow  from  aluminum  to  steel,  a  chemical  change 
occurs  in  the  aluminum,  making  it  a  non-conductor  and  choking  off  tin- 
flow.  Thus  a  current  of  60-cycle  frequency,  after  passing  through  a  one- 
cell  rectifier    becomes  practically    (there  i~  a   slighl    inverse  current)    a 


X-RAY  MACHINES 


25 


uni-dircctional  current  with  30  interruptions  per  second.  If,  after  passing 
through  the  rectifier,  as  just  described,  the  current  is  an  interrupted  one, 
the  questions  arise :  Why  send  it  through  an  interrupter?  Why  not 
directly  on  to  the  coil  ?  Because  the  interruptions  are  not  sharp  and 
complete  enough.     The  current  is  pulsating  rather  than  interruupted. 

By  connecting  three  or  four  rectifier  cells  in  a  certain  way  (Fig.  28), 
we  are  able  to  obtain  practically  a  uni-directional,  constant  current. 

If  the  supply  current  is  60-cycle,  as  is  usually  the  case,  the  electrolyte 
in  the  interrupter  remains  the  same  as  for  a  D.C.,  no-volt  circuit  namely, 


Fig.     22.     Vibrator     or    mechanical     interrupter. 


about  20  per  cent.,  but  if  the  A.C.  supply  is  133-cycle,  the  solution  should 
be  stronger — about  30  per  cent. 

From  the  interrupter  the  current  passes  into  the  rheostat,  as  per 
Fig.  17. 

A  rheostat  (Fig.  29)  is  an  apparatus  by  the  use 
Rheostat.  of  which  we  are  enabled  to  regulate  the  quantity  of 

electricity  entering  an  electric  machine.    The  rheostat 
does  not  have  much  effect  on  voltage. 

Fig.  30  illustrates  the  rheostat.  A  represents  coils  of  wire,  often 
German  silver,  offering  great  resistance  to  the  flow  of  electricity.  When 
the  arm,  B,  is  on  button  1,  the  current  must  pass  through  all  the  re- 
sistive wire  on  its  way  to  the  electric  machine,  induction  coil,  motor,  or 
what  not.  This  resistive  wire  chokes  back  amperage.  On  button,  2, 
there  is  less  resistance  ;  on  button,  3  still  less,  until  on  the  last  button  the 
current  passes  directly   into  the  machine.     The   rheostat  illustrated  acts 


-' 


ELEMENTARY  RADIOGRAPHY 


also  as  a  switch,  completely  breaking  the  current  when  the  arm,  B,  is  on 
button,  o. 

From  the  rheostat  the  current  passes  into  the  coil  proper,  follows 
the  wire  of  the  primary  winding,  and  passes  back  through  the  negative 
lead  wire  to  the  mains. 


<2** 


Fig.    -'::.     Seven-point    electrolytic    interrupter,    water-cooled. 


A  different  method  of  wiring  to  that  shown  in  Fig.  17  is  illustrate-1 
in  Fig.  31.  At  first  glance  it  seems  that  the  primary  current  is  not  inter- 
rupted, the  interrupter  being  on  the  negative  wire  with  the  current  pass- 
through  it  after  passing  through  the  coil.  But  since  the  current  can- 
not enter  the  coil  any  faster  than  it  leaves  the  manner  of  its  exit  will 
govern  it-  entrance,  and  hence  the  current  of  the  primary  is  interrupted 
just  the  same,  whether  the  interrupter  be  placd  On  the  positive  or  nega- 
tive lead  wire. 


X-RAY  MACHIXES 


27 


The  coil  consists  of  a  soft  iron,  cylindrical  core, 

gOll#  around  which  is  wrapped  insulated  copper  wire,  the 

primary    winding.      (Fig.  32.)      (The    necessity    for 

good  insulation  will  be  appreciated  it   we  stop  to  consider  what  would 


si 


w= 


Fig.    -'4.     Acid    hydrometer. 


happen  if  the  core  were  wound  with  uninsulated  wire.  If  this  were  done 
the  current  would  not  follow  the  windings  of  the  wire  at  all.  but  would 
choose  the  shorter  path  of  less  resistance,  passing  along  the  iron  core, 
making  a  short  circuit.  )  (  )ver  the  primary  winding  is  placed  a  heavy 
insulation  of  mica  or  vulcanite,  and  around  this  is  wound  more  insulated 
wire    the  secondary  winding.      (Figs.  32  and  33.) 

There  is  positively  no  electric  connection  between  the  primary  and 
secondary  windings.     The  primary  current  passes  through  the  primary 


2S 


ELEMEXTARY  RADIOGRAPHY 


winding  and  into  the  negative  lead  wire.     But  in  its  passage  it  has  in- 
duced or  created  a  secondary  current  in  the  secondary  winding. 

Coils  are  rated  and  designated  according  to  the  maximum  num- 
ber of  inches  of  atmosphere  the  secondary  current  can  be  made  to  jump. 
As  the  current  jumps  from  one  terminal  to  the  other  of  the  secondary 
winding,  a  spark  occurs,  due  to  the  resistance  of  the  atmosphere  to  the 


P 

n 


t 


4- 


B 


Fig.  25. 


Fig.  26. 


Fig.   25.      A.   movable   arm   with   fulcrum    at    B.      C,   electro-magnet.      D,   break.      E,   spring. 
Fig.    26.     A,    piece    of    ribbon    steel.      B,    point    where    circuit    is    broken.      C,    electro-magnet. 


flow  of  the  current.  When  we  speak  of  a  coil  as,  say  a  12-inch  coil,  we 
mean  that  the  spark  gap  of  that  coil  is  twelve  inches  long;  that  its  sec- 
ondary current  can  be  made  to  jump  twelve  inches  of  atmosphere.  The 
larger  the  coil  the  longer  the  spark  gap.  From  6-inch  to  as  high  as  40- 
inch  coils  are  manufactured.  From  8-inch  to  about  18-inch  coils  are  the 
sizes  generally  used. 

The  wire  of  the  primary  winding  is  from  \ 2-  to  8-gauge;  of  the  sec- 
ondary from  34-  to  29-gaUge.  The  length  of  the  windings  varies  accord- 
ing to  the  size  of  the  coil,  of  course.  The  wire  in  the  primary  of  a  [2-inch 
coil  is  about  100  feet  long,  in  the  secondary  about  28  miles  long.  The 
win-  in  the  primary  of  an  [8-inch  coil  is  about  [40  feet,  and  in  the  sec- 
ondary 38  miles  long. 


X-RAY  MACHIXES 


29 


Fig.    27.     One-cell    rectifier. 


-     S8       Three-cell   rectirk 


3° 


ELEMENTARY   RADIOGRAPHY 


At  each  "make"  and  "break"  of  the  circuit  of  the  primary  current, 
a  current  is  induced  in  the  secondary.  The  secondary  current  induced 
ai  ;he  break  of  the  primary  Hows  in  the  same  direction  as  the  current  in 
the  primary,  while  the  current  induced  at  the  make  flows  in  the  opposite 
direction.  Thus  the  secondary  is  an  alternating  current;  but  the  current 
oi  the  make  is  SO  much  weaker  than  the  current  of  the  break  that,  for 
practical  purpose,  the  secondary  may  be  considered  a  uni-directional,  pul- 


Fig.   39.     Twenty-nine   button   rheostat. 


sating  current.  The  current  of  the  make  is  what  is  known  as  the  inverse 
current,  and  it  is  the  effort  of  all  coil  manufacturers  to  make  a  coil  giving 
a>  little  inverse  current  as  possible. 

The  voltage  of  the  secondary  current  cannot  lie  determined  ac- 
curately. Authorities  differ  very  greatly  in  their  estimate  of  the  number 
of  volts  required  to  jump  one  inch  of  atmosphere,  giving  the  figure  as 
low  a-   kkxx),  and  as  high  as  6o,000.     What   voltage  is  required  to  jump 

each  succeeding  inch  after  the  fust,  j^  also  a  question  shrouded  in  very 

greal    uncertainty. 

Estimating  each  inch  of  atmosphere  at    10,000  volts,  which  perhaps 
tting  a-  near  the  truth  a-  possible  ai  the  present  time,  the  voltage 


X-RAY  MACHINES 


31 


furnished  by  any  size  coil  can  easily  be  determined.  Figuring  on  this 
basis,  an  8-inch  coil  in  full  operation  supplies  a  current  with  a  potential 
of  80,000  volts;  a  20-inch  coil,  200,000  volts. 

The  amperage,  or,  to  be  more  exact,  the  milliamperage  of  the  sec- 
ondary current  of  an  induction   coil  varies  according  to  the   resistance 


Fig.    30.      Diagram    of    rheostat. 


through  which  the  current  is  forced.  Thus,  allowing  the  rheostat  to  re- 
main on  the  same  button,  the  milliamperage  is  increased  or  decreased 
accordingly  as  the  spark  gap  (Fig.  17)  is  shortened  or  lengthened.  With 
the  spark  gap  at  its  maximum  length,  the  milliamperage  is  least.  As  the 
sliding  rods  are  pushed  closer  to  one  another,  so  lessening  the  length  of 
the  spark  gap,  milliamperage  increases.  Different  coils  are  capable  of 
forcing  different  milliamperages  through  their  maximum  length  of  spark 
gap.     Thus  one   10-inch  coil  may  be  able  to   force  twenty  milliamperes 


32 


ELEMENTARY  RADIOGRAPHY 


through  ten  inches  of  atmosphere,  while  another  could  send  only  two 
milliamperes  through  such  a  resistance.  All  coils  give  a  high  milliam- 
perage  on  a  short  spark  gap,  the  amount  running  into  hundreds  of  mil- 
liamperes. Instead  of  the  sliding  rods,  some  coils  have  an  arrangement, 
as  per  Fig.  34.  for  regulating  the  length  of  spark  gap. 

The   milliamperage   strength   can   he   estimated   roughly  by   the   ap- 
pearance of  the  spark.     A  thin,  blue  spark  indicates  low  amperage.     A 

Mains 


Y 


Inierrupter 


Coil 


Fig.  31. 


fat,  fuzzy  spark,  the  caterpillar  spark,  indicates  high  milliamperage.  To 
do  rapid  dental  radiographic  work  a  coil  should  give  at  least  six  inches 
of  the  fat,  fuzzy  spark. 

Amperemeters  and  milliamperemeters  are  used  on  the  primary  and 
secondary  current-,  respectively,  to  measure  their  volume.  (Fig.  13.) 
While  these  meters  may  be  considered  luxuries  rather  than  necessities, 
they  are  certainly  ver\    useful  luxuries. 

How  dangerous  are  the  currents  of  an  induction 
Colli  coil?  is  a  question  often  asked.     Both  primary  and 

Dangerous.  ondary  currents  of  an   induction  coil  are  danger- 

ous.    The  larger  the-  coil  the  greater  the  danger.     Tf 
one  should  come  in  contact  with  a  terminal  of  the  coil,  he  would  receive 
'•re.  painful  shock.      It  would  he  much   more  severe  and  painful   if 


X-RAY  MACHINES 


33 


the  victim  happened  to  be  standing  on  a  conductor,  for  then  the  current 
would  pass  entirely  through  the  body  into  the  conductor.  If  one  should 
come  in  contact  with  both  terminals  of  a  large  coil,  so  that  the  entire 
current  would  pass  through  the  body,  the  accident  might  result  fatally. 


Fig.  ss: 

A,  iron  core.     B.  iron  core  with  primary  winding.     C,  iron  core,  primary  winding  and  insulation. 
D,   iron   core,   primary   winding,   insulation   and   secondary   winding. 


Now    let    us    consider   the    high-frequency   coil. 
fiifllvTrequency         (Figs.   14  and  35.)      In  mechanical  construction  the 
Coil.  high-frequency    coil    may   be    considered    a    kind    of 

double  coil  with  the  secondary  of  the  first  coil  act- 
ing as  the  primary  of  the  second  coil.  The  primary  current  of  the  first 
coil  should  be  A.C. 


3.;  ELEMENTARY  RADIOGRAPHY 

From  the  supply  wire  the  current  passes  through  the  primary  wind- 
ing of  a  step-up  transformer  |  first  coil )  at  the  usual  commercial  ioo  to 
125  volts,  no-cycle.  (Fig.  35.)  An  alternating  current  of  the  same 
frequency  as  the  primary,  but  higher  in  voltage  and  lower  in  amperage 
is  generated  in  the  secondary  of  the  transformer,  and  passes  into  the 
condenser,  which  acts  as  a  reservoir.  As  the  current  leaves  the  condenser 
ami  jumps  the  regulating  spark  gap.  it  is  oscillating  at  a  frequency  of 


Fig.  33 

Cross-section    diagram    of    induction    coil.      A,    iron    core.       B,    primary    winding.      C,    insulation. 

D,   secondary    winding. 


from  10.000  to  more  than  a  million.  It  passes  through  the  primary  wind- 
ing of  the  Tesla  coil,  inducing  a  secondary  current  of  the  same  high 
frequency.  This  Tesla  coil  is  the  same  as  an  induction  coil  (  Figs.  32  and 
33),  except  that  some  inert  substance,  instead  of  soft  iron,  is  used  for 
the  core. 

The  secondary  current  of  the  second  coil  is  the  one  supplied  by  the 
machine,  the  one  to  be  used  to  generate  X-rays.  Like  the  current  of  the 
Kuhmkortl.  or  induction  coil,  this  current  is  high  in  voltage  and  low  in 
amperage.  The  current  1  f  the  induction  coil  is,  however,  practically  a 
uni-directional  one.  while  the  current  supplied  by  the  high-frequency  coil 
is  alternating  at  the  inconceivably  high  frequency  of  tens  of  thousands 
or  million-.  Hence  the  term  "high  frequency,"  which  is  applied  to  the 
current  and  the  coil  producing  it. 

The  frequency  is  governed  by  the  size  of  the  condenser;  the  smallet 
the  condenser  the  higher  the  frequency.  Tims  most  "high-frequency  and 
X-ray  machine-"  are  equipped  with  a  switch,  by  means  of  which  all,  or 


X-RAY  MACHINES 


35 


a  part,  of  the  condenser  may  be  used.  When  using  the  coil  for  X-ray 
work,  this  switch  should  be  turned  to  "low  frequency,"  so  that  all  of  the 
condenser  is  used.  When  using  the  coil  for  "high-frequency"  treatments 
— using  the  current  as  a  therapeutic  agent — the  switch  should  be  on  "high 
frequency,"  so  that  only  a  part  of  the  condenser  is  used. 

By  means  of  the  regulating  spark  gap,  we  can  control  to  an  extent 
the  secondary   current  of  the   second  coil — the  current   supplied   by   the 


Fig.   84. 


machine  for  use.  Widening  the  gap  increases  voltage  at  the  expense  of 
the  amperage;  narrowing  the  gap  increases  amperage  at  the  expense  of 
the  voltage.  The  wattage  remains  the  same.  For  X-ray  work  the  gap 
should  be  as  short  as  possible,  without  reducing  the  voltage  to  a  point 
where  the  current  will  not  pass  through  the  X-ray  tube. 

The  ideal  current  for  exciting  an  X-ray  tube  ( in  other  words,  pro- 
ducing X-rays)  is  a  uni-directional  one.  Compared  with  that  of  the 
high-frequency  coil  the  current  of  the  induction  coil  more  nearly  ap- 
proaches this  ideal.  Because  of  this,  the  writer  advises  the  use  of  the 
induction  coil  in  preference  to  the  high-frequency  coil,  unless  a  very 
small  machine  is  desired.  We  thus  eliminate  large  high-frequency  coils 
from   further  consideration. 

The  small,  portable,  suitcase,  high-frequency  coils  called  "X-ray 
and  high-frequency  coils,"  may  be  used  where  the  lack  of  space  makes 
the  installment  of  a  larger  machine  impossible  or  undesirable,  when  a 
transportable  coil  is  wanted,  and  when  the  purchaser  wishes  to  make  the 
minimum  cash  investment. 


36 


ELEMENTARY  RADIOGRAPHY 


As  stated,  the  primary,  or  supply,  current  of  a  coil,  built  on  the  high- 
frequency  plan  illustrated,  should  be  A.C.  When  attaching  the  portable 
coil  (Fig.  14)  on  an  A.C.  circuit,  therefore,  all  that  needs  to  be  done  is 
to  screw  the  attachment  into  a  lamp  socket. 


Terminal  Spark   Cap 
(Aoi  rejulatinj  spark  <}ap) 


znJ  Coil      m 


Tesla  Coil 


Regalatinf 
Spdrk  (sap 


Condenser 


11' Coil 

or 
Step  -  Up 
Transformer 


secondary 


71717771717^ 


Primzjy 


JeconcLa-riy 


Pr-ifna.ry 

r.//./ /'/vv 


-K=> 


Fig.  35. 


When  the  supply  current  is  D.C.,  a  rotary  cori- 

Rotary  verter  should  be  used.    A  rotary  converter  I  Fig.  36) 

Converter.  consists  of  an  electric  motor  set  in  motion   by  the 

supply   current,   which   motor   in   turn   revolves   the 

armature  of  an  A.C.  dynamo,  which  generates  the  electricity  that  is  sent 

into  the  coil.     Instead  of  having  the  D.C.  motor  and  the  A..C.  generator 

eparate  machines  connected  by  a  common  shaft    so  that  movement  of 

armature  of  one  machine  revolves  the  armature  of  the  other,  the 

rotary  converter  can  be  made  si  >  as  n  1  be  end'  ised  in  one  casing.   (  Fig.  1 5. 1 

Tracing  the  current,  as  per   Fig.  37«  coming  through  the   fuse  and 

!:.  the  current  passes  through  the  positive  wire  to  the  starting  box 


X-RAY   MA  CHINES 


V 


or  rheostat.  it  leaves  the  starting  box  through  two  wires,  passing 
through  one  to  the  field  of  the  motor  marked  S.F.,  through  the  other  to 
the  armature  of  the  motor,  marked  ARM,  and  out  of  the  motor  through 
the  negative  lead  wire.  A  new  circuit  is  formed  from  the  generator  side 
of  the  converter  marked  A.C.,  passing  through  the  coil. 

It  may  be  well  to  state  just  here  that  an  electric  motor  is.  in  con- 
struction, practically  the  same  as  a  dynamo  or  generator.     In  fact,  taking 


Fig.    36.     Rotary    converter,    or    motor-dynamo. 


a  given  machine,  it  may  be  used  as  either  a  dynamo  or  a  motor.  If  its 
armature  is  revolved  by  some  power,  it  will  generate  electricity,  and  it 
is  then  a  dynamo ;  if  a  current  of  electricity  is  sent  into  its  field  and 
armature,  the  armature  revolves ;  and  it  is  then  an  electric  motor.  Motors 
are  made  to  be  operated  by  both  D.C.  and  A.C.  circuits ;  that  is,  we  have 
D.C.  motors  which  can  be  run  only  by  a  direct  current,  and  A.C.  motors 
which  can  be  excited  only  by  an  alternating  current. 

Instead  of  a  rotary  converter,  some  machines  are  equipped  with  a 
mechanical  vibrator  (Fig.  22),  which  interrupts  the  current  as  it  enters 
the  coil.  This  is  not  so  efficacious  as  the  converter.  Machines  with  the 
mechanical  interrupter  are  advertised  to  operate  on  either  A.C.  or  D.C. 
circuits. 

The  length  of  the  spark  gaps  of  portable  machines  varies  from  four 
to  ten  inches.  They  are  seldom  able  to  give  a  fat,  fuzzy  spark  longer 
than  half  the  length  of  the  spark  gap.  The  full-length  spark  is  almost 
alwavs  thin  and  blue. 


38 


ELEMENTARY  RADIOGRAPHY 


As  a  general   proposition  the  alternating  is  the 

Danger  of  most  dangerous  of  electric  currents.    Mysterious  and 

Currents.  surprising  as  it  is,  however,  high-frequency  currents, 

such  as  high-frequency  coils  produce,  are  much  less 

dangerous  than  the  current  of  an  induction  coil.     If  one  should  touch  a 


Line, 
J 10  Direct  Current 


Portable  Coil. 


converter 


Fig.   37. 


terminal  of  a  high-frequencj  coil  a  spark  would  jump  to  the  hand  just 
as  it  came  within  sparking  distance  of  the  terminal.  This  spark  might 
make  a  blister,  hut  if  the  experimenter  had  been  standing  on  a  non-con- 
ductor, no  further  discomfort  would  he  felt.  Indeed,  one  may  take  a 
small   steel   bar   ami.    standing  on   a    non-conductor,   touch    a   terminal    of 

oil  and  -o  take  into  the  body  enough  current  to  cause  great  injury, 
if  it  were  of  the  nature  of  the  induction  coil,  without  receiving  any  sen- 
sation at  all.  If  he  should  stand  on  a  conductor,  however,  the  shock 
would  he  painful.  If  he  should  grasp  both  terminals,  so  that  the  entire 
current  passed  through  the-  body,  the  result  would  be  severe  pain  and 
probably  injury.    Tin-  larger  the  coil  the  more  dangerous  the  current. 

'The  primary  current  of  the  portable  high- frequency  coils  is  not  as 
dangerous  as  the  primary  current  of  the  stationary  induction  coils,  he- 


X-RAY  MACHINES 


39 


cause  they  draw  cnly  from  three  to  ten  amperes,  while  the  induction  coils 
seldom  draw  less  than  twenty  and  as  high  as  sixty  amperes. 

The  "interrupterless"  coil,  or  transformer,  as  it 
TnlcrruptcrlCSS         is  often  called  (Fig.  15).  is  the  newest  and  perhaps 
Coil.  the    most   powerful   X-ray   machine   made.     On   the 

market  these  coils  are  known  by  such  trade  names 
as  "The  Snook  Roentgen  Apparatus,"  "The  Peerless  Roentgen  Appa- 
ratus,"  "The    Solace   Interrupterless." 


Fig.    38.     Interrupterless    coil,    showing    switch    and    rheostat,    rotary    convtrtcr,    transformer    and 

rectifying   switch. 


The  interrupterless  coil  consists  of  a  rotary  converter,  a  step-up 
transformer,  and  a  rectifier  switch.  (Fig.  38.)  The  step-up  transformer 
may  he  of  the  closed  magnetic  circuit  core  type  (Fig.  10),  or  the  open 
core  type  (Fig.  32).  These  machines  are  of  two  kinds:  Those  built  to 
be  operated  on  a  D.C.  circuit,  and  those  designed  for  the  A.C.  circuit. 

Let  us  consider  the  former  first :  The  converter  is  set  in  motion  by 
the  commercial  direct  current.  It  generates  an  alternating  current  which 
is  sent  through  the  primary  of  the  transformer.  The  induced  current  in 
the  secondary  is  of  the  proper  voltage  and  amperage  for  X-ray  work,  but 
it  is  alternating.  It  should  be  direct.  It  is  made  so  by  means  of  the 
rectifying  switch,  and  is  then  an  ideal  current  for  X-ray  work.  The 
rectifying  switch  is  a  revolving  mechanical  device  similar  to  a  commu- 
tator in  principle. 


40  ELEMENTARY  RADIOGRAPHY 

The  A.C.  machine  is  similar  to  the  D.C.  machine,  the  principal 
difference  being  the  addition  of  an  A.C.  motor.  An  alternating  cur- 
rent motor  transmits  mechanical  power  to  the  "rotary  converter," 
which,  in  this  case,  becomes  simply  an  A.C.  generator,  not.  strictly  speak- 
ing, a  rotary  converter,  though  it  is  usually  so  called. 

Since  the  supply  current  is  alternating,  and  it  is  an  alternating  cur- 
rent that  must  be  sent  into  the  primary  of  the  coil,  one  may  logically  ask, 
\\  h\  not  send  the  commercial  current  directly  into  the  primary,  instead 
of  operating  an  A.C.  motor,  which,  in  turn,  revolves  the  armature  of  an 
A.C.  generator,  which  produces  the  current  which  is  sent  into  the  coil  ? 
The  answer  is  that  the  rectifier  switch  must  work  in  synchronism  with 
the  generator,  which  supplies  the  current  to  the  coil.  In  other  words,  the 
rectifier  switch  must  be  on  the  same  shaft,  and  revolve  in  unison  with  the 
generator  in  order  to  rectify  the  alternating  current  induced  in  the  sec- 
ondary winding  of  the  coil. 

The  interrupterless  coils  are  rated  according  to  the  amount  of 
"energy"  they  create,  not  according  to  their  spark  gap  length.  The  spark 
gap  is  usually  ten  or  twelve  inches  long.  The  machines  are  rated  to  have 
a  capacity  of  so  many  kilowatts.  Take  a  "4  kilowatt"  machine,  for  ex- 
ample. Its  primary  current,  we  will  say,  is  100  volts,  40  amperes  (4,000 
watts),  the  secondary  current  something  like  100,000  volts,  40  milliam- 
peres  (4,000  watts).  This  system  of  rating  is  being  adopted  by  manu- 
facturers of  induction  coils  also. 


CHAPTER  III. 
X-Fay  tubes  and  the  X-Rays. 

Thus  far  we  have  considered  only  the  electric  phase  of  the  subject. 
We  shall  now  describe  the  apparatus  through  which  the  electricity  is 
passed,  and  which  generates  the  X-rays,  namely  the  X-ray  tube. 

An  X-ray  tube  is  a  bulbular  glass  tube,  from  which  the  atmosphere 
has  been  exhausted  to  quite  a  high  degree  of  vacuum — about  1/1,000,000 
part  of  an  atmosphere.  It  should  be  remembered  that  there  is  a  some- 
thing which  occupies  all  space,  even  vacuua,  and  that  something  is  known 
as  ether.  There  is,  of  course,  ether  in  the  X-ray  tube.  X-ray  tubes  are 
often  called  Crooke's  tubes,  but  they  resemble  the  tube  made  by  Pro- 
fessor Crooke  only  in  having  a  high  degree  of  vacuum.  In  mechanical 
construction  they  are  quite  different. 

Tubes  may  be  divided  into  two  classes :  those  designed  to  be  used 
on  an  induction  coil  or  interrupterless  coil,  and  those  made  to  be  used 
on  a  high-frequency  coil.     We  shall  describe  the  former  first. 

Sealed   in   the  X-ray  tube   are  the  anode.   Fig. 

Simple  39,  A  (also  called  anti-cathode  and  target),  and  the 

Cubes.  cathode,  B.     The  anode  is  usually  flat,  placed  at  an 

angle  of  45  degrees  to  the  long  axis  of  the  tube,  and 

made  of   some  high-fusing  metal,   such   as  platinum,   iridio-platinum   or 

tantalum.     The  cathode  is  concave,  saucer  shape,  and  usually  made  of 

aluminum. 

Since,  in  connecting  the  tube  to  the  coil,  it  is  necessary  to  attach  the 
connecting  terminal  tape  or  wire  from  the  positive  side  of  the  coil  to  the 
target  end  of  the  tube,  we  must  be  able  to  determine  which  is  the  positive 
terminal  of  the  coil.  This  may  be  done  on  an  induction  coil,  as  follows : 
Cut  out  the  resistance  of  the  rheostat,  adjust  the  sliding  rods  to  about 
one-half  the  distance  of  the  maximum  spark  gap,  and  throw  on  the 
switch.  The  spark  will  jump  the  gap  so  quickly  that  it  is  impossible  to 
learn  by  simple  observation  in  which  direction  it  is  traveling.     By  watch- 

41 


4- 


ELEMENT.  IRY   RADIOGRAPHY 


ing  the   large   disc   terminal,   however,   this  can   be  determined.      If   on 

throwing  the  switch  on  and  off  the  spark  is  noticed  to  cling  to  the  edge 
of  the  disc  always,  then  the  current  is  passing  from  the  disc.  If,  how- 
ever, the  spark  occurs  from  the  surface  of  the  disc  just  as  the  current  is 
turned  on  (  it  may  then  seek  the  edges),  the  current  is  traveling  from  the 
small  bulb  to  the  disc.     (Fig.  40.) 

With    the  tube  properly  connected  to  the   coil   as   per  Fig.  41.   the 
current  is  shunted   (Fig.  42)   through  the  tube,  instead  of  jumping  the 


+ 


«fc 


A  B 

'.     A.  anode.     B.  cathode.     C,  point  at  which  the  atmosphere  was  pumped   from   the  tube. 


spark  gap,  passing  from  anode  to  cathode.  Whether  the  current  will 
choose  the  path  through  the  tube  or  jump  the  spark  gap  depends  on 
which  offers  the  less  resistance.  A  current  of  electricity  always  travels 
the  path  1  >f  least  resistance. 

Tubes  are  designated  according  to  the  degree  of  their  vacuum.  Thus 
we  have  the  high  or  hard  tube,  in  which  the  vacuum  is  well-nigh  com- 
plete; the  medium  tube  in  which  the  vacuum  is  less  complete,  and  the 
-.ft  or  low  tube,  in  which  the  vacuum  is  least  complete.  High  tube- 
offer  the  greatest  resistance  to  the  passage  of  the  electric  current  through 
them,  then  comes  the  medium,  while  the  low  vacuum  tube  oilers  the  least 
resistance.  For  dental  picture  work  a  tube  should  be  high  or  medium. 
preferably  high. 

The  operator  may  determine  whether  a  tube  is  bard,  medium  or 
-oft.  ;t,  follow-:  Conned  tin-  tube  to  the  coil.  (Fig.  41.1  Separate  the 
sliding  ro.l-  to  give  a  spark  gap  of  two  or  three  inches  and  turn  on  the 
current.  I  Inless  the  tube  is  very  low  indeed,  the  current  will  jump  the 
soark  gap  instead  of  passing  through  the  tube.     Let  us  suppose  the  cur- 


X-RAY  TUBES  AND  THE  X-RAYS 


43 


rent  does  jump  the  spark  gap.  Now  widen  the  gap  a  little;  turn  on  the 
current,  and  it  passes  through  the  tube.  The  tube  will,  therefore,  be 
rated  as  one  of  low  vacuum,  offering  a  resistance  slightly  greater  than 
two  or  three  inches  of  atmosphere.  When  the  current  jumps  the  spark- 
gap  instead  of  passing  through  the  tube,  the  tube  is  said  to  have  "backed 
up"  so  many  inches — the  number  of  inches  of  the  gap — of  ''parallel 
spark."     Thus  a  low  tube  will  hack  up  two  or  three  inches  of  parallel 


A 


+ 


A 


<- 


-*m 


A 


+ 


P 


^ — > 


Fig.    40. 


spark  ;  a  medium  tube  will  back  up  four  or  live  inches  of  spark ;  a  high 
tube  will  back  up  six  or  seven  inches  of  spark,  and  a  very  high  tube  will 
back  up  eight  or  nine  inches  of  spark.  Aery  high  tubes  offer  so  much 
resistance  that  only  the  largest  coils  are  able  to  force  sufficient  milliam- 
perage  through  them  to  generate  a  sufficient  number  of  X-rays  for  picture 
work.  A  tube  that  will  back  up  more  than  nine  inches  of  spark  is  too 
high  to  be  useful ;  it  is  impossible  to  force  enough  milliamperage 
through  it. 

From  the  foregoing  it  will  be  seen  that  any  coil  smaller  than  one 
with  an  eight-inch  spark  gap  could  not  well  excite  a  high  tube,  and  that 
at  least  a  ten-inch  coil  is  necessary  to  light  a  very  high  tube.  It  seems, 
too,  that  any  coil  with  a  spark  gap  wider  than  eight  or  ten  inches  is  need- 
lessly large.  The  coils  with  the  long  spark  gaps  are,  however,  seldom 
able  to  throw  a  fat,  fuzzy  spark  farther  than  eight  or  ten  inches.  The 
throwing  of  a  thin,  blue  spark  a  greater  distance  is  simply  incidental  and 


44 


ELEUEXTARY   RADIOGRAPHY 


without  practical  usefulness.  Thus  an  eight  or  ten-inch  coil  may  be  as 
powerful  as  one  with  an  eighteen  or  thirty-inch  spark  gap;  that  is, 
capable  of  forcing  as  high  a  milliamperage  through  a  high  tube.  If. 
however,  a  coil  can  force  any  kind  of  a  spark  at  all  through  from  eighteen 
t<>  thirty  inches  of  atmosphere,  we  may  be  sure  it  will  send  a  high  milliam- 
perage through  a  good  radiographic  tube,  or,  what  is  the  tube's  equivalent 


Fig.    41.     The    X-ray    tube    connected    with    the    induction    coil. 


in  resistance,  six  or  eight  inches  of  atmosphere.  It  is  so  well  understood 
to-day  that  the  coil  with  the  very  wide  spark  gap  is  not  necessarily  more 
powerful,  that  manufacturers  arc  making  practically  all  of  their  coils 
witb  from  an  eight  to  a  twelve-inch  spark  gap,  then  rating  them  ac- 
cording to  the  milliamperage  they  can   force  through  this   resistance. 

To  light  a  tube  well  a  coil  should  be  capable  of  giving  a    fat.    fu/.zy 
spark,  tin'  distance  of  the  parallel  spark  which  the  tube  backs  up. 

The  tube  thus   far  described   is  the  simplesl    form  of   X-ray  tube. 
Xext  in  simplicity  is  the  bi-anodal  tube      |  Fig.  43.) 

When  the   two  anodes  are  connected,  as   in    Fig. 

Bi-anodal  43-  the  positive  terminal  may  be  attached  to  either 

Cubes.  anode  or  assistanl  anode,  preferably  the  anode.    The 

advantage  of  tin-  assistanl  anode  is  a  matter  on  which 

authorities   have   widely   different    opinions.      <  >ne   manufacturer,   a   man 


X-RAY  TUBUS  AND   THE  X-RAYS 


45 


who  is  making  one  of  the  very  best  tubes  on  the  market,  tells  me  that  he 
puts  the  assistant  anode  in  his  tubes  because  some  of  his  customers  de- 
mand it.  and  he  is  able  to  do  so  without  impairing  their  efficiency;  that 
his  tubes  would  be  just  as  good  with  but  one  anode.  Remember  the 
vacuum  of  an  X-ray  tube  is  not  perfect ;  there  are  some  gases  in  the  tube. 
The  function  of  the  assistant  anode  is  to  draw  these  gases  back  of  it 
away   from  between  anode  and   cathode.     Thus,   if  the   removable   wire 


W^- 


RESISTANCE 


vVWVAAAAAA 


m- 


m- 


THE  SHUNT 

Fig.    42.     The   arrows   show    the    current    flowing   through    the    shunt. 


connecting  the  anode  and  assistant  anode  (Fig.  43)  be  removed  and  the 
tube  hitched  to  the  coil,  the  positive  terminal  being  attached  to  the  anode, 
the  tube  will  work  with  a  slightly  lower  vacuum,  because  the  assistant 
anode  does  not  draw  gases  back  of  it.  Tubes  with  assistant  anodes  are 
supposed  to  be  capable  of  transmitting  a  greater  milliamperage. 

We  have  divided  X-ray  tubes  into  two  grand  classes :  those  designed 
to  operate  on  an  induction  coil  or  interrupterless  coil,  and  those  designed 
to  operate  on  a  high-frequency  coil.  Each  of  these  classes  may  be  sub- 
divided into  tubes  with  a  means  for  regulating  their  vacuum  (Fig.  44), 
and  tubes  without  a  means  for  regulating  their  vacuum  (Figs.  39  and  43). 

Tubes  without  regulators  are  no  longer  in  general  use.  because,  with 
use.  they  soon  become  too  hard  and  must  be  sent  back  to  the  manufac- 
turers to  be  opened  and  repumped.  This  is  expensive  and  annoying.  A 
tube  too  high  for  use  will  sometimes  drop  in  vacuum  and  regain  its 
former  usefulness  if  allowed  to  rest — remain  unused — for  a  month  or  so. 

There   are   different   methods  of   regulating  the 

methods  Of  vacuum  of  X-ray  tubes.     The  most  popular  and  effi- 

Rcqulanna  cient  is  the  one  we  shall  new  consider. 

Uacuum.  The  vacuum  is  governed  by  means  of  a  movable 

arm,   which   increases   or  decreases   the  distance  be- 


4" 


ELEMEXTARY  RADIOGR.  iPHY 


tween  A  and  B,  Fig.  44.     This  distance  we  shall  call  the  tube-regulating 

spark  gap.    The  shorter  the  gap  the  lower  the  vacuum  can  be  made;  that 
is.  the  shorter  the  gap  the  less  perfect  the  vacuum  can  he  made. 

The  current  enters  the  tube  and,  let  us  imagine,  tries  to  pass  from 
anode  to  cathode.     The  vacuum  in  the  center  of  the  tube  is  more  perfect 


REMOVABLE 
WIRE 


A5SISTANT 
"ANODE 


> 


CATHODE 


ANODE 

Fig.    43.     A    Bi-Anodal    X-ray    tube. 


REGULATING  CHAMBER 


Fig.    11.     X-ray   tube   with   vacuum    regulator. 


than  around  the  walls.     I  knee  the  path  of  least  resistance  is  through  the 
regulating  chamber,  through   the  movable  arm.   through  the  tube-regu- 
lating -park  gap.  into  the  negative  terminal  tape;  unless    of  course,  the 
lating   -park  gap  is  very  wide. 


X-RAY  TUBES  AND  THE  X-RAYS 


47 


F!g.    4-").      Showing    the    manner    of    connecting    the    third    terminal    on    the    coil    with    the 

regulating  chaml  er. 

The  regulating  chamber  contains  asbestos  impregnated  with  some 
chemical,  sodium  or  potassium  hydrate,  for  examples.  When  the  current 
passes  through  the  regulating  chamber,  heat  is  create  '.  which  causes  the 
chemical  to  give  off  gases.  These  gases  lower  the  vacuum  of  the  tube 
so  that  the  current  may  pass  directly  from  anode  to  cathode.     When  the 


4* 


ELEMENTARY  RADIOGRAPHY 


tube  cools  thoroughly — in  the  course  of  fifteen  to  thirty  minutes — these 
gases  are  taken  up  again  by  the  chemicals  in  the  regulating  chamber,  and 
the  vacuum  rises  again.  Thus  the  vacuum  of  the  tube  is  always  too  high 
when  the  tube  is  not  in  use,  but  can  be  lowered  to  the  desired  degree. 
For  rapid  picture  work,  the  tube-regulating  spark  gap  should  be  three 


CATHODE 
STREAM 


Fig.   46.     Showing   the  direct    X-ray  and   the  cathode   stream. 


to  five  inches.     As  the  tube  gets  old  the  tube-regulating  spark  gap  must 
be  made  shorter  to  obtain  the  same  condition  of  tube. 

When  the  tube  is  properly  hitched  to  the  coil  and  the  movable  arm 
:or  a  high  vacuum — to  give  a  regulating  spark  gap  of  about  four 
inches— and  the  current  turned  on,  practically  all  the  current  will  at  first 
pass  through  the  regulating  chamber  and  jump  the  tube-regulating  spark 
gap.  As  explained,  this  lowers  the  vacuum,  ami  in  a  few  seconds  the 
currenl  i-  passing  from  anode  to  cathode.     All  of  the  current  ma)   pass 

directly  through  the  tube  now    for  a   few   seconds,  hut   the  passage  of  the 

current   from  anode  t<»  cathode  raises  the  vacuum  and  presently  some 

current  will  he  seen  to  jump  the  gap  for  a  while.     And  so  mi,  just  as  the 

vacuum  raises  ;i  little,  it  is  immediately  lowered  by  some  of  the  current 
sing  through  the  regulating  chamber. 


X-RAY  TUBUS  AND   THE  X-RAYS  49 

Instead  of  the  movable  arm,  a  terminal  tape  and  a  third  terminal 
on  the  coil  may  be  used.  (Fig.  45.)  Thus  the  tube-regulating  spark  is 
transferred  from  the  tube  to  the  coil.  The  hitching  of  a  tube  to  a  coil 
with  a  third  terminal  is  very  simple.  Hitch  the  positive  terminal  to  the 
anode,  or  assistant  anode  if  desired,  and  the  negative  terminal  to  the 
cathode  as  usual ;  and  the  third  terminal  to  the  regulating  chamber.  The 
advantages  of  the  third  terminal  over  the  movable  arm  are  that  the  spark- 
ing is  taken  awa\  from  the  tube  and  so  away  from  the  patient  (in  radio- 
graphic work  the  tube  is  always  near  the  patient),  and.  on  some  coils. 
Fig.  13  for  example,  the  gap  may  be  regulated  from  the  end  of  the  coil 
where  the  rheostat  and  switches  are  located,  so  making  it  unnecessary 
for  the  operator  to  move  from  his  position  to  change  the  tube-regulating 
spark  gap. 

When  the  current  passes  from  anode  to  cathode,  the  cathode 
stream  (Fig.  46)  is  given  off  from  the  cathode.  The  cathode  stream 
is  a  form  of  vibratory  motion  of  the  ether.  Leaving  the  concave  surface 
of  the  cathode,  the  cathode  stream  is  focused  to  strike  the  anode  or  target 
at  a  point.  X-rays  are  given  off  from  this  point  (Fig.  46).  The  cathode 
stream  can  be  seen  in  a  tube  of  very  low  vacuum,  appearing  blue. 

Great  heat  is  generated  at  the  point  on  the  target  where  the 
cathode  stream  strikes  it.  Hence  the  necessity  of  making  the  target  of 
some  very  high  fusing  metal.  A  small  hole  may  be  burned  superficially 
into  the  target  without  spoiling  the  tube.  The  tube  in  Fig.  47  has  a 
long  sheath  of  metal  connected  with  the  target  to  take  up  the  heat.  Tubes 
are  made  with  a  means  for  cooling  with  water.  These  are  intended  for 
treatment  rather  than  picture  work,  though  they  may  be  used  for  the 
latter. 

X-rays  were  discovered  by  William  Conrad  Roentgen,  professor  of 
physics  at  the  Royal  University  of  Wurzburg,  Germany,  in  the  summer 
of  1895.  Roentgen  applied  the  name  X-rays  because  he  did  not  know 
just  what  he  had  discovered;  X.  the  algebraic  symbol  for  the  unknown, 
being  adopted  to  signify  this  ignorance.  They  were  not  called  X-rays 
because  the  rays  cross,  forming  an  X,  as  is  popularly  supposed. 

The  Roentgen  Congress,  in  Berlin,  1905,  adopted  a  uniform  set  of 
technical  terms  in  which  the  word  Roentgen  always  occurred.  Thus  we 
have  the  phrase  Roentgen  ray  for  X-ray  and  such  words  as  Roentgen- 
ology, Roentgenologists,  Roentgenogram,  etc.,  etc.  While  approving  of 
a  move  for  a  uniform  nomenclature,  many  of  the  new  words  are  long 
and  unwieldy  and  the  writer  shall,  in  this  work,  use  many  of  the  old  and 
better-known  terms. 

X-ravs  are  invisible,  vibratorv  waves  of  or  in  the  ether.     The  most 


So 


ELEMENTARY  RADIOGRAPHY 


popular  theory  is  that  they  are  light  waves  with  an  inconceivably  rapid 
rate  of  vibration.  Red  light  rays  vibrate  at  the  rate  of  four  hundred 
billion  per  second;  violet  rays  vibrate  at  the  rate  of  seven  hundred  and 


l'"ig.    17.     X-iay  tube   properly  lit   up 


;  ray   tube    with   the   current   passing   through   it    in    the    wrong   dii  i 


fifty  billion  ],<v  second.     The  intermediate  colors — blue,  green,  yellow  and 
orange-  vibrate  at  intermediate  degrees  of  rapidity. 

Though  human  vision  is  limited  to  about  three  hundred  and  fifty 
billion  variance,  the  difference  between  four  hundred  billion  and  seven 
hundred  and  fifty  billion,  may  we  not  fairly  assume  that  there  are  light 


X-RAY  TUBES  AND  THE  X-RAYS 


5i 


rays  of  a  higher  and  lower  vibration  invisible  to  us?  Ultra-violet  rays 
have  a  more  rapid  vibration  than  violet  rays,  and  have  no  action  on  the 
retina,  and  are  therefore  invisible.  X-rays  vibrate  more  rapidly  than 
ultra-violet  rays.  The  rapidity  of  their  vibration  is  estimated  at  288,- 
224,000,000,000,000*  (two  hundred  and  eighty-eight  quadrillions,  two 
hundred  and  twenty-four  trillions — French  notation )    per  second. 


Fig.    49.      The    inverse   spark   gap   on   the    left   is   open,    on    the    right   is    closed. 


When  light  strikes  an  object  and  can  be  seen  as  light,  it  is  because 
the  light  is  reflected  from  the  object  to  the  eye.  X-rays  are  invisible 
because  they  cannot  be  reflected.  When  they  strike  an  object  they  are 
either  absorbed  or  pass  through  it.  X-rays  are  not  discernible  to  any 
of  the  special  senses.  They  pass  from  the  focal  point  on  the  target  in 
regular,  diverging  lines.  (Fig.  46.)  They  cannot  be  reflected,  refracted, 
or  condensed,  and  penetrate  objects  directly  according  to  the  density  of 
the  object. 

The  passing  of  the  X-rays  through  the  glass  of  the  tube  gives  rise 
to  a  green  fluorescence  (green  light)  in  the  active  hemisphere — the  hemi- 
sphere in  front  of  the  target — of  the  tube.  Whether  a  tube  is  working 
well  or  not  can  be  determined  by  this  fluorescence.  There  should  be  a 
definite  line  of  demarcation  between  the  active  and  inactive  hemispheres 
of  the  tube.  A  tube  working  properly  should  light  up  as  per  Fig.  47. 
The  light  is  never  quite  steady;  it  wavers  a  little.  High,  medium  and 
low  tubes  give  slightly  different  fluorescences  when  in  operation.  The 
fluorescence  from  a  high  tube  is  a  very  light  yellowish  green  ;  from  a  low 


*Custer's  "Dental  Electricity." 


ELEMENTARY  RADIOGRAPHY 


tube  a  bluish  green  and  from  a  medium  tube  an  intermediate  shade  of 
green. 

Just  here  let  it  be  said  that  an  exact  colored  picture  of  an  X-ray 
tube  in  operation  has  never  been  made.  I  obtained  the  services  of  an 
artist  and  spent  a  great  many  hours  on  the  work,  but  was  unable  to  make 
a   picture   worthy  of   reproduction.     The   light   from   an   X-ray   tube   in 


Fig.   50.      Series  spark   gap. 


operation  is  of  a  peculiar  brilliancy  that  cannot  be  reproduced  in  crayons, 
water-colors,  or  ink. 

When  the  vacuum  of  a  tube  is  so  low  as  to  render  it  useless  for  radio- 
graphic purposes,  a  definite  blue  color  can  be  seen  here  and  there  in  the 
tube,  the  cathode  stream  can  sometimes  be  seen  appearing  blue,  and  the 
line  of  demarcation  between  the  active  and  inactive  hemispheres  of  the 
tube  is  not  well  defined. 

When  a  tube  is  punctured  the  vacuum  gets  very  low,  of  course,  and 
its  appearance  in  operation  may  be  as  just  described,  or,  as  sometimes 
occurs,  it  gives  rise  to  a  fluorescence  as  variegated  as  a  rainbow,  or  it  may 
not  light  at  all.  A  punctured  tube  can  sometimes  be  repaired  by  the 
manufacturer. 

When  the  vacuum  of  a  tube  is  too  high,  the  tube  lights  up  reluctantly 
a  very  yellowish  green,  and  the  line  of  demarcation  is  not  at  all  distinct. 

Fig.  48  illustrates  fairly  well  the  appearance  of  a  tube  with  the 
current  passing  through  it  in  the  wrong  direction.  When  this  condition 
is  seen  the  current  must  be  turned  off  quickly,  or  the  tube  will  be  ruined. 
Sometimes,  when  the  tube  is  properly  hitched  to  the  coil  lighl  rings  back 
<>f  the  target,  similar  to  those  shown  in   Fig.  4K,  may  he  seen.     'Phis 


X-RAY  TUBES  AND  THE  X-RAYS 


53 


signifies  that  the  coil  is  generating  considerable  inverse  current.  Recall 
that,  while  the  current  generated  by  the  induction  coil  is  practically  a 
unidirectional  one,  there  is  an  inverse  current  which  is  sometimes  strong 
enough  to  manifest  itself  as  just  mentioned,  especially  when  the  vacuum 
of  the  tube  is  low. 


Fig.    51.      A   triple   valve   tube. 


There  are  several  ways  to  keep  this  inverse  cur- 

Cuttirtfl  Out  rent  from  passing  through  the  tube.     The  simplest 

Tnpersc  way  is  to  make  a  spark  gap  between  the  coil  and 

Current.  terminal  tape,  which  gap,  for  want  of  a  better  name, 

I  shall  call  the  inverse  spark  gap,  since  it  is  used  to 

cut  out  the  inverse  current.    ( Fig.  49. )    This  gap  may  be  made  at  either  the 

positive  or  negative  terminal,  or  both,  as  is  found  necessary.     It  cuts  out 

the  inverse  current  because  this  current  is  comparatively  weak,  not  strong 

enough  to  jump  the  gap  and  pass  through  the  tube.     The  main  current 

jumps  the  gap  easily.     Unless  inverse  current  is  observed  in   the  tube 

there  should  be  no  inverse  spark  gap — the  little  sliding  rods  should  touch 

the  binding  posts  of  the  terminal  tapes.     (Fig.  49.) 

Series  spark  gaps  (Fig.  50)  may  be  used  between  the  coil  and 
terminal  tape  to  cut  out  the  "inverse."  The  current  passes  easily  from 
point  to  disc,  but  reluctantly  from  disc  to  point.  Thus  the  series  spark 
gap  may  be  used  to  cut  out  inverse  current  from  a  tube,  with  the  points 
toward  the  positive  terminal  tape  and  the  points  away  from  the  negative 
terminal  tape.  Fig.  50  shows  the  points  toward  the  positive  terminal 
tape.  They  should  be  turned  in  the  opposite  direction  at  the  negative 
terminal — away  from  the  tape. 


54 


ELEMENTARY  RADIOGRAI'l  1) 


The  third,  last,  and  the  most  efficient  means  of  cutting  the 
inverse  current  out  of  an  X-ray  tube  is  by  means  of  a  valve  tube.  ( Fig. 
51.)  The  valve,  <<r  Yillard  tube,  is  a  tube  of  low,  or,  as  it  is  often  called, 
<  Teissier  vacuum — 1/1,000  to  3/1,000  of  an  atmosphere — with  a  disc 
electrode  and  a  spiral  electrode,  both  made  of  aluminum.  The  exact 
reason  for  its  action  is  not  known,  but  the  electric  current  cannot  travel 


Fig.  52. 


A. 


An  oscillimeter. 


through  it  well  except  in  one  direction — from  disc  to  spiral.  Thus,  to 
cut  out  inverse  current  the  disc  end  of  the  valve  may  be  attached  to  the 
I>o>itive  terminal  tape  of  the  coil,  and,  by  means  of  a  piece  of  conducting 
tape,  or  wire,  the  spiral  end  connected  with  the  target  side  of  the  tube. 
Or  the  disc  end  of  the  valve  may  be  attached,  with  a  piece  of  conducting 
tape,  to  the  cathode  side  of  the  tube  and  the  spiral  end  of  the  valve  to  the 
negative  terminal  tape  of  the  coil.      (Fig.  52.) 

It  is  claimed  by  some  that  the  valve  tube  acts  only  as  an  additional 
tance  t<-  the  flow  of  the  inverse  current,  cutting  it  out  of  the  X-ray 
tube  in  the  same  manner  that  the  inverse  and  multiple  spark  gaps  do. 

The  oscillimeter,  <>r  oscilloscope  (  Fig.  53)  is  a 

Oscillimeter.  '  Teissier   vacuum   tube   with   two  straight  aluminum 

electrodes.      When    a    unidirectional    current    passes 

through    it    a    violet    light    accurs    at    tin-    negative    electrode.      When    an 


X-RAY  TUBES  AND   THE  X-RAYS 


55 


alternating  current  passes  through  it  the  light  occurs  at  both  electrodes. 
When  the  current  sent  through  it  is  stronger  in  one  direction  than  in  the 
other  the  electrodes  light  unevenly,  the  brighter  electrode  representing 
the  negative  of  the  stronger  current. 

The  oscillimeter  is  made  to  be  used  between  the  coil  and  the  tube, 


Fig.    54.      The    Meyer    penetrometer. 


Fig.    55.      A    fluoroscope. 


when  the  latter  is  covered,  to  detect  inverse  current.     I  have  never  felt 
the  need  of  it,  though  I  use  an  opaque  shield  over  my  tube. 

As  has  been  stated,  the  X-rays  are  not  discernible 
Demonstration  to  an^  0*  tne  sPec'al  senses.     Their  existence,  how- 

Of  X-Rays.  ever,  can  be  demonstrated  as  follows : 

Place  an  X-ray  tube  in  a  wooden  box  so  that 
when  the  current  is  sent  through  it  no  fluorescence  can  be  seen.     Excite 


56  ELEMENTARY  RADIOGRAPHY 

the  tube  in  a  dark  room  and  approach  it  with  some  object  coated  with 
calcium  tungstate  or  platino-barium  cyanide,  and  the  object  will  be  seen 
to  fluoresce  or  glow  something  like  phosphorus.  This  fluorescence  is 
due  to  the  action  of  the  X-rays  (which  penetrate  the  wood  of  the  box 
easily)  on  the  calcium  tungstate  or  platino-barium  cyanide.  Hence  the 
closer  the  object  to  the  tube  the  more  and  stronger  the  X-rays  which 
strike  it.  and  the  brighter  the  fluorescence. 

X-rays  from  different  tubes  differ  in  length  and 
Power  Of  power  of  penetration.     A  low  tube  gives  the  shortest 

Penetration  and  least  penetrating  X-rays ;  then  comes  the  medium 

Of  X-Rays.  tube,  while  the  X-rays  from  a  high  tube  are  longest 

and  most  penetrating. 
The  degree  of  penetration  may  be  determined  by  means  of  a  pene- 
trometer. (Fig.  54.)  This  particular  kind  of  a  penetrometer  consists  of 
two  small  flat  pieces  of  wood  fastened  together,  with  a  sheet  of  lead  be- 
tween them.  Holes  are  made  through  both  wood  and  lead.  Into  these 
holes  are  placed  thin  metal  discs  which  just  fit  the  holes.  The  different 
holes  receive  different  numbers  of  discs. 

To  use  this  style  of  penetrometer  we  must  have  a  fluoroscope.  A 
fluoroscope  (Fig.  55)  consists  of  a  light  proof  box,'  tapered  and  made  to 
fit  over  the  eyes  at  one  end,  and  covered  at  the  other  end  with  pasteboard 
coated  with  calcium  tungstate  or  platino-barium  cyanide.  If  one  should 
look  into  the  fluoroscope  holding  it  toward  ordinary  light  nothing  could 
be  seen — one  would  look  into  perfect  darkness.  But  if  the  fluoroscope 
should  be  held  so  that  the  X-ray  struck  its  screen — i.  e.,  the  pastboard 
covered  with  calcium  tungstate  or  platino-barium  cyanide — it  would  be 
seen  to  fluoresce,  or  glow,  or  light  up. 

If  now  the  penetrometer  is  held  between  the  fluoroscope  and  the 
source  of  the  X-rays  a  shadow  will  be  seen  on  the  screen,  because  the 
lead  in  the  penetrometer  is  opaque  to  X-rays.  Whether  the  X-rays  will 
penetrate  the  metal  in  the  holes  depends  on  how  much  metal  there  is  to 
penetrate  and  how  penetrating  the  X-rays  are.  Thus  the  more  penetrat- 
ing the  rays  the  more  holes  can  be  seen. 

There  are  a  great  many  different  kinds  of  penetrometers.  I  shall 
not  describe  them  here,  but  will  give  the  scale  of  the  two  most  popular, 
the   Benoist  and  the   Walter,  together  with  that  of  the   Meyer   (  Fig.  54). 

Benoist.         Walter.         Meyei 

Soft,  or  low  tube 1 —  2  t  i —  2 

Medium 3 —  5  2 — 3  3 —  4 

Hard  or  high    6 — 12  4 — 6  5 — IO 


X-RAY  TUBES  AND   THE  X-RAYS 


57 


While  the  penetrometer  is  a  very  valuable  appliance,  it  is  far  from 
being  a  necessity  in  the  practice  of  dental  radiography. 

As  X-rays  pass  through  the  glass  of  the  tube 

Secondary  more   X-rays  are  generated.     These  are   known   as 

Ray$.  "secondary  rays."    They  are  short  and  feeble  and  do 

not  travel  parallel  with  the  direct  X-rays,  but  pass 


Fig.   56.      High-frequency    X-ray   tube. 


Fig.    57.      High-frequency    X-ray    tube. 


out  from  the  tube  in  every  direction  intersecting  the  direct  rays.  Second- 
ary rays  are  also  given  off  from  any  object  which  X-rays  strike.  Thus, 
direct  rays  will  strike  a  wall ;  secondary  rays  are  given  off  from  the  wall 
and  strike  the  other  walls,  the  Moor,  and  the  ceiling,  whereupon  a  new 
set  of  X-rays,  tertiary  rays,  are  produced.  When  the  tertiary  rays  strike 
an  object  still  another  set  of  X-rays  are  generated,  and  so  on,  each  new 
set  of  rays  being  much  shorter  and  weaker  than  the  former.  So  a  room 
in  which  an  X-ray  tube  is  excited  is  filled  with  X-rays — not  with  the 
direct  rays,  but  with  the  comparatively  feeble  and  inconsequential  sec- 
ondarv,  tertiary  and  other  subordinate  rays. 


58 


ELEMENTARY   RADIOGRAPHY 


X-ray  tubes  are  of   different  sizes.     The  bulb 
X-Ray   Cubes.  varies  in  diameter  from  five  to  eight  inches.     Thus 

we  have  the  five-inch  tube,  six-inch  tube,  and  so  on. 
The  six-inch  tube  is  about  right  for  dental  work. 

With  use  the  glass  of  the  active  hemisphere  of  the  tube  discolors  to 
a  purplish  color.     This  does  not  materially  affect  the  tube. 

The  fatal  injury  to  most  tubes  is  a  puncture.     One  means  of  guard- 
ing against  punctures  is  to  keep  the  tube  clean.     "A  fruitful  cause  of 


Fig.    58.      Tube   rack    for    tubes    when    not    in    use. 


puncture  is  the  discharging  of  the  current  from  the  tube  into  the  rack  on 
which  the  tube  is  kept  when  not  in  use.  The  tube  may  have  been  dis- 
charged by  the  operator  touching  the  terminals  before  putting  the  tube 
away,  but  if  the  tubes  are  stored  in  the  same  room  where  high-frequency 
and  other  coil  discharges  are  taking  place,  they  will  recharge  themselves 
from  the  atmosphere  and  discharge  onto  the  rack,  no  matter  of  what 
material  the-  rack  may  be  made.  A  safe  way  of  putting  away  tubes  is  to 
connect  the  anode  and  cathode  terminals  together  1>\  a  wire  during  the 
time   the  tube   is  at   rest." 

The  general  principle-  of  construction  of  the  high-frequency  X-ray 
tube  |  Figs.  56  and  57)  arc  those  already  given  in  the  description  of  the 
tube-,  built  to  be  operated  by  a  unidirectional  current.     The  chief  differ- 


X-RAY  TUBES  AND  THE  X-RAYS 


59 


ence  between  the  high-frequency  tubes  and  those  already  described  lies 
in  the  different  mean  resorted  to  in  the  former  to  dispose  of  one  direction 
or  wave  of  the  alternating  current,  or,  to  speak  more  definitely,  one 
cathode  stream. 


^4w 


Fig-   59.  Fig.   60. 

Fig.  59.     Plain   X-ray  tube   stand. 
Fig.    60.     Tube    stand,    with    a    lead    glass    protection    shield    and    a    compression    diaphragm. 


Either  end  of  a  high-frequency  X-ray  tube  may  be  connected  with 
either  terminal  tape  of  a  high-frequency  coil.  While  this  is  theoretically 
true,  it  will  sometimes  be  found  in  practice  that  the  tube  works  better 
hitched  up  one  way  than  the  other. 

When  the  tube  is  hitched  up  the  current  oscillates  through  it  and 
two  cathode  streams  are  generated.  One  of  the  streams  is  focussed 
against  the  target  and  X-rays  are  given  off  from  the  focal  point,  while 


6o 


ELEMENTARY   RADIOGRAPHY 


the  other  is  focused  into  a  funnel  in  the  back  of  the  target.  (Fig.  56.) 
X-rays  cannot  be  given  off  from  this  funnel ;  hence  the  tube  lights  up  in 
the  active  hemisphere  as  illustrated  in  Fig.  47.     This  funnel  scheme  is 


Fig.  61.     A   pedestal,   with  a  lead  glass  protection   shield,   compression   diaphragm   and 

plate  holder. 


one  way  of  taking  care  of  one  cathode  stream  while  the  other  is  being 
used  for  X-ray  production.  Another  scheme  is  to  move  one  cathode  back 
so  far  that  the  cathode  stream  focuses  before  reaching  the  back  of  the 
target.     (Fig.  17.) 

The  high-frequency  tube  ma)  be  used  to  advantage  on  an  induction 
coil  which  is  generating  a  great  deal  of  inverse  current. 

One  may  wonder  why  a  valve  (Fig.  51)  or  a  rectifier  (Fig.  27) 
could  nol  be  used  to  CUt  OUl  the  flow  of  current  in  one  direction,  and  a 
tube  like  the  one  in  Fig.  44.  for  example,  used  on  a  high-frequency 
coil.      Xeitbcr  the  valve   nor  the  rectifier  is  capable  of   cutting  out  one 


X-RAY  TUBES  AND   THE  X-RAYS 


61 


direction  of  flow  of  a  current  of  such  high  potential  (voltage).  The 
valve  is  able  to  cut  out  the  inverse  current  of  an  induction  coil  because 
it  (the  inverse  current)  is  comparatively  weak;  and  the  rectifier  can  cut 
out  one  wave  of  the  commercial  A.C.,  because  the  voltage  is  only  a  little 
over  a  hundred.  The  voltage  of  the  high-frequency  coil  is  perhaps  a 
hundred  thousand. 


Fig.    62.      Table,    with   a    lead    glass    protection    shield    and    compression    diaphragm. 


To  avoid  "straining"  a  tube,  it  should  not  be  again  used,  after  hav- 
ing been  used  till  hot,  until  it  has  cooled  thoroughly.  Overheating  the 
tube  will  destroy  the  gases  in  it,  and  so  raise  the  vacuum  to  such  a  degree 
as  to  make  it  impossible  to  force  a  sufficient  milliamperage  through  it  to 
produce  a  sufficient  number  of  X-rays.  Sending  a  very  strong  current 
through  a  tube  of  low  vacuum  will  also  destroy  the  gases  of  the  tube  and 
spoil — strain — it. 

Fig.  58  is  a  tube  rack  for  holding  the  tube  when  not  in  use. 

It  is  obvious  that  there  must  be  some  kind  of  a  device  for  holding 
the  tube  when  in  use.  This  may  be  either  a  plain  tube  stand  (Fig.  59), 
or  a  tube  stand  with  a  lead  glass,  protection  shield  and  a  compression 


62 


ELEMEN  T.  IRY  RADIOGRAPH ) ' 


X-RAY  TUBES  JXD  THE  X-RAYS 


63 


diaphragm  1  Fig.  60).  or  a  pedestal  with  a  lead  glass  protection  shield, 
compression  diaphragm,  and  plate  holder  (Fig.  61),  or  a  table  with  a 
lead  glass,  protection  shield  and  compression  diaphragm.     (Fig.  62.) 

Dr.  Blum,  of  New  York,  uses  a  wall  bracket  fixture  to  support  a 
lead  glass,  protection  shield  and  o  ■mpression  diaphragm.  The  tube,  one 
of    the    water-cooled    type,    is    seen    fitting    into    the    lead    glass    shield. 


Fig.    6i.      A    Protection    Shield. 


(Fig.  63.)  This  would  be,  I  imagine,  a  very  adaptable  and  satisfactory 
apparatus. 

A  tube  stand  should  be  heavy  enough  to  be  firm  and  not  allow  any 
vibration  of  the  tube  while  in  use.  The  parts  coming  in  contact  with  the 
tube  must  be  made  of  an  electric  non-conducting  material ;  otherwise  the 
current  would  pass  from  the  tube  into  them,  so  puncturing  the  tube. 

The  uses  of  the  compression  diaphragm  are :  To  hold  the  patient 
immovable ;  to  compress  the  soft  parts  as  when  making  a  picture  of  the 
kidney,  for  example  ;  to  aid  the  operator  in  directing  the  rays  through  a 
part  at  the  proper  angle  and  to  cut  out  the  secondary  rays  given  off  from 
the  tube. 

A  protection  shield,  often  called  a  Friedlander's  shield  (Fig.  64), 
which  is  opaque  to  X-rays  except  for  the  window  or  opening  in  it,  and 
which  is  used  to  cover  X-ray  tubes,  also  cuts  out  some,  but  not  all.  second - 
arv  ravs  given  off  from  the  glass  of  the  tube.    Thus  if  the  Xravs  from  an 


64 


ELEMENTARY  RADIOGRAPHY 


X-ray  tube  are  directed  on  a  part  through  a  diaphragm,  only  the  direct 
rays  strike  the  part,  as  in  the  diagram  study  shown  in  Fig.  65.  While, 
with  the  Friedlander  shield,  some  of  the  secondary  rays  might  strike  the 
part  also.     (Fig.  66.) 


Fig.    65.      D    U    O,    direct    ray.      S    S.    secondary    ray.       1'    I',    part. 


Fig.  66.     I>   i>    l».   direct    ray-.     S   S.   secondary   rays.      P   P.   part. 


When  there  i>  inverse  current  passing  through  a  tube  supplemental 
X-rays  are  produced  thereby.  It  is  desirable  thai  these  rays  should  not 
strike  the  plate  when  making  a  picture.  Either  a  compression  diaphragm, 
or  a  protection  shield  will  cut  out  these  rays  -or  at  least  most  of  them. 


CHAPTER    IV. 
making  Radiographs. 

The  X-ray  picture  is  variously  called  radiograph,  skiagraph.  Roent- 
genograph, radiogram,  skiagram  and  Roentgenogram.  The  word  radi- 
ograph is  a  combination  of  a  Latin  and  Greek  word  meaning  ray  and 
urite  or  record.  The  word  skiagraph  (spelled  also  sciagraph)  is  a  com- 
bination of  two  Greek  words  meaning  sliade  or  shadozu  and  write  or  re- 
cord. The  word  Roentgenograph  is  a  combination  of  a  proper  name, 
Roentgen,  and  the  Greek  word  meaning  write  or  record.  The  terminal 
gram  occurring  in  the  words  radiogram,  skiagram  and  Roentgenogram 
— as  well  as  the  more  common  words  such  as  telegram,  program,  epi- 
gram, and  others — is  of  Greek  origin  and  denotes  that  which  is  written 
or  marked. 

The  use  of  the  X-rays  for  radiographic  work  depends  on  two  prop- 
erties of  the  rays.  First,  they  penetrate  substances  in  direct  proportion 
to  the  density  of  the  substance,  and  second,  they  affect  the  photographic 
plate  or  film  the  same  as  white  light  does. 

A  photographic  plate  is  a  piece  of  transparent 

Photographic  plate  glass   about  an  eighth  of  an  inch  thick,  one 

Plates,  side    of    which    is    coated    with    an    emulsion    of 

a  silver  salt,  usually  gilver  bromide,  and  gela- 
tine, albumen,  or  collodion.  The  use  of  the  gelatine,  albumen  or 
collodion  is  simply  to  stick  the  salt  to  the  glass.  When  a  thin 
coating  of  this  emulsion  has  dried  on  the  glass  we  have  what  is 
called  the  photographic  "dry  plate."  In  appearance  it  is  similar  to  trans- 
lucent greenish-white  glass,  but  on  close  inspection  one  is  able  to  de- 
tect that  one  side  is  a  little  less  glossy  than  the  other.  The  less  glossy 
is  the  coated  side,  also  called  the  sensitive,  the  film,  or  the  emulsion  side 
of  the  plate.  The  term  "dry  plate"  is  to-day  an  almost  superfluous  one, 
practically  all  the  plates  used  being  dry  plates.  There  is,  however,  a 
photographic  plate  known  as  the  "wet  plate,"  but,  since  it  is  never  used 
in  radiography,  I  shall  not  describe  it. 


66  ELEMENTARY  RADIOGRAPHY 

The  dry  plate  is  made  in  the  absence  of  white  light,  put  up  in  light- 
proof  packages,  and  so  supplied  to  consumers.  These  packages  must 
not  be  opened  except  in  a  dark  room,  for  the  slightest  exposure  to  a 
white  light  will  spoil  them. 

The  difference  between  the  photographic  dry  plate  and  the  photo- 
graphic film  is  only  that  the  plate  is  a  piece  of  glass  coated  with  a 
silver  salt,  while  the  film  is  a  thin  sheet  of  transparent  celluloid  coated 
with  a  silver  salt.  As  with  the  plate,  the  sensitive  side  of  the  film  is  a 
little  less  glossy  than  the  uncoated  side.  The  film  curls  slightly  toward 
the  coated  side,  unless  it  is  of  the  "non-curling"  variety,  when  it  is 
straight,  or  may  even  curl  slightly  away  from  the  coated  side. 

X-ray  pictures  may  be  taken  on  ordinary  photo- 
Special  graphic  plates  or  films  made  to  be  used  in  cameras. 

X-ray  Plates  While  this  may  be  done,  the  results  obtained  are  not 

and  Tilms,  nearly   so  good   as   when  special  X-ray  plates  and 

films  are  used.  The  special  X-ray  plates  and  films  dif- 
fer from  the  ordinary  plates  and  films  in  that  a  thicker  coating  of  the 
emulsion  is  put  on  them.  This  is  sometimes  accomplished  by  coating  the 
celluloid  or  glass  two  or  three  times,  one  coat  on  another.  When  this  is 
done  the  film  or  plate  is  said  to  be  multi-coated.  X-ray  films  and  plates 
should  not  only  be  thickly  coated,  but,  which  is  more  important,  should 
also  be  extremely  sensitive — that  is,  easily  acted  upon  by  light — for, 
though  the  X-rays  have  a  wonderful  power  of  penetration,  their  action 
on  the  silver  emulsion  is  feeble  compared  to  the  white  light  of  day. 

The  following  manufacturers  make  X-ray  plates  of  any  desired  size: 
The  Eastman  Kodak  Company,  Rochester,  N.  Y. ;  Cramer  Dry  Plate 
Company,  New  York  City;  Hammer  Dry  Plate  Company,  St.  Louis,  Mo. ; 
The  Lumiere  X.  A.  Company,  Burlington,  Vt. ;  and  the  Ilford  Mfg.  Co.. 
flford,  London,  England  (American  agents  for  Ilford  goods,  E.  15.  Mey- 
rowitz,  104  East  23d  Street.  New  York  City).  But  two  manufacturers, 
the  Ilford  M  ig.  Co.,  London,  England  the  Eastman  Kodak  Co.,  Rochester. 
X.  Y.,  make  special   X-ray  films. 

I  wish  here  to  advise  against  buying  large  quantities  of  either  plates 
or  films  at  a  time.     They  deteriorate  in  a  few  months. 

The  making  of  a  radiograph  of  the  hand  is  one 
technic  of  °*  tne  s'mP^est  operations  in  radiography,  and   for 

making  that  reason  it  will  be  described  to  teach  elementary 

Radiographs.  principles.    The  following  technic  of  making  a  radio- 

graph will,  of  necessity,  be  much  broken  into  by 
descriptions  of  materials  and  appliances  used. 

A    5  x  7-inch   plate   i-  about   the   righl    size   to  make  a   radiograph  of 


MAKING  RADIOGRAPHS 


67 


the  hand.  Plates  are  supplied  by  the  manufacturer  packed  in  light-proof 
boxes,  holding  usually  one  dozen  plates,  with  the  warning  on  the  box. 
"Open  only  in  a  dark  room."  The  "dark  room"  is  simply  what  the  name 
states — a  room  from  which  light  is  excluded.  A  closet  without  a  window 
makes  a  good  dark  room,  except  that  there  is  seldom  running  water  in  it. 
It  is  not  absolutely  necessary  to  have  running  water  in  the  dark  room, 
but  it  is  very  convenient.     If  a  closet  cannot  be  utilized  a  room,  light- 


Fig.   67.     To  left,   window  ready   for  frame.     When   frame   is  in   position  the   metal   catches  arc 
turned  to  hold  it.     The  frame  fits  inside  of  the  strip  on  the  sill.     Figure  to  right  shows 

frame    in    position. 


proof  except  for  one  window,  may  be  made  dark  by  covering  the  window 
with  a  frame  on  which  is  tacked  some  material  such  as  the  leather  or 
rubber  used  for  side  and  storm  curtains  in  buggies.  If  this  material  does 
not  completely  turn  the  light,  it  should  be  painted  with  thick  black  paint. 
The  frame  should  be  made  to  fit  over,  not  into,  the  window  casing.  (Fig. 
67.)  With  the  frame  so  placed,  if  a  little  light  comes  in  around  it.  it 
does  not  come  directly  into  the  room,  but  is  reflected  to  the  side.  The 
more  perfect  the  darkness  of  the  room  the  better,  but  the  very  little  light 


oS 


ELEMENTARY  RADIOGRAPHY 


which  can  enter  through  a  window  with  the  blind  drawn  down,  and  with 
a  well-made  frame  over  it  will  not  cause  any  trouble.  If  the  door  to  the 
room  permits  light  to  leak  in  around  it.  such  light  should  also  be  shut  out. 
It  would  be  impossible,  of  course,  to  work  to  any  advantage  in  a 
perfectly  dark  room,  for  we  could  not  see  what  we  were  doing.  Hence' 
the  necessity  of  having  a  dark  room  lantern  (Fig.  68).  which  will  give 
sufficient  light  to  guide  us  in  our  work,  without  being  of  such  nature  as 
to  have  any  act  inn  on  plates  or  films.     The  term  "developing  light" — the 


Fig.   68.     Dark    room   lantern. 


ligbt  given  by  the  dark  room  lantern — may  mislead  one  to  believe  that 
the  light  in  some  way  aids  in  developing  a  plate  by  its  action  on  it.  But 
such  is  not  the  case.  The  light  is  of  value  only  because  it  enables  the 
worker  to  sec.  The  light  may  be  a  candle,  a  coal  nil  lamp,  or  an  incan- 
descent electric  light  shining  through  red  glass.  While  such  a  lantern 
can  easily  he  made,  the  writer  warns  against  it,  for.  though  the  light  of  a 
home-made  lantern  may  appear  the  same  to  the  eye  as  the  light  of  the 
lanterns  manufactured  by  photographic  supply  manufacturers,  its  action 
mi  a  plate  or  film  may  he  disastrously  different.  The  lantern  shown  in 
Fig.  68  consists  of  ;i  [6-candle  power  incandescent  lighl  with  a  frosted 
glass  hulh.  in  a  light-proof  tin  box,  the  front  of  which  is  of  removable 
glass.     The  light    shines  first    through   the    frosted  .^lass  of   the  hulh,  then 

an  orange-colored  j^lass,  then  a  ruby  glass. 

In  the  dark  room,  with  only  the  light  of  the  dark  room  lantern  we 


M.IK  IXC  RADIOGRAPHS 


69 


open  our  box  of  plates,*  take  out  one,  carefully  close  the  box,  and  place 
the  plate  in  an  envelope  of  black,  light-proof  paper  just  large  enough  to 
receive  it.  Now  place  plate,  black  envelope,  ct  <//.,  in  another  envelope 
of  black  and  orange-colored  paper,  putting  the  open  end  of  the  first  en- 
velope in  hrst.  We  may  now  expose  this  package  to  ordinary  daylight 
and  artificial  light  with  impunity,  and  the  plate  is  ready  for  use  in  the 
making  of  a  radiograph.  These  envelopes  are  obtained  from  the  plate 
manufacturers. 


Fig.    C9.      Shoeing    how    to    handle    a    plate    by    its    edges. 


While  in  the  dark  room,  before  putting  the  plate  in  the  envelope,  we 
must  note  which  is  the  sensitive  side,  and  bear  this  in  mind  until  the 
outside  envelope  is  marked  properly  to  designate  it.  As  formerly  stated, 
the  sensitive  side  is  a  little  less  glossy.  Another  way  to  determine  which 
is  the  coated  side  is  to  look  through  the  plate  just  at  the  edge.  When 
the  glass  side  is  up,  one  is  able  to  look  through  the  glass  and  see  the  film 
beneath.  The  sensitive  side  of  the  plate  should  present  toward  the 
smooth  side  of  the  envelope — away  from  the  seam  side. 

The  plate  should  be  handled  by  the  edges.  (  Fig.  69. )  This  applies 
to  the  handling  of  the  plate  at  all  times,  and  to  the  handling  of  the  film 
as  well.    Unless  the  fingers  are  wet  or  greasy,  touching  the  sensitive  side 


*Experienced  photographers  prefer  to  handle  sensitive  plates  in  ahsolute  dark- 
ness, and  soon  learn  to  detect  the  film  side  of  the  plate  by  feeling  lightly  with  the 
fingers,  thus  obviating  the  need  of  the  dark  room  light  when  "loading"  plates. — Ed. 


70 


ELEMENTARY  RADIOGRAPHY 


of  the  plate  is  not  likely  to  result  in  spotting  the  picture,  but  it  is  always 
well  to  eliminate  as  many  chances  of  failure  as  possible. 

We  are  now  ready  to  arrange  tube,  hand,  and  plate  in  their  proper 
relative  positions  to  take  the  picture.     In  all  radiographic  work  it  must 


STA/VD 


Fig.  ~».  Showing  relative  positions  of  tube,  h; 


ml  plate  for  making  a  radiograph  of  the  hand. 


niily  ho  borne  in  mind  that  we  are  making  a  shadow  picture;  that 
we  are  simply  throwing  a  shadow  on  the  plate,  using  X-rays  as  the 
source  of  light. 

Lay  the  plate  on  a  stand,  sensitive  side  up.  Place  the  hand  on  the 
plate.  Adjust,  the  tube  at  a  variable  distance  directly  above  the  band. 
(Fig.  jo.) 


MAKING  RADIOGRAPHS  71 

The  distance  from  the  tube  to  the  hand  may  vary  from  about  10  to 
20  inches,  measurements  being  taken  from  the  target,  not  from  the  glass 
of  the  tube.  It  is  not  necessary  to  have  the  target  and  the  plate  parallel 
to  one  another  (in  the  same  plane)  as  some  writers  direct.  On  the  con- 
trary, the  position  as  in  Fig.  70  is  a  better  arrangement. 

Assuming  now  that  the  tube  is  properly  hitched  to  the  coil  and  work- 
ing properly,  we  are  ready  to  make  the  exposure — to  take  the  picture. 

In  giving  demonstrations,  I  find  that  at  this  point  someone  invariably 
volunteers  to  "turn  out  the  light."  This  is  not  necessary.  The  only 
reason  for  having  the  rooms  even  slightly  darkened  is  to  enable  the  ope- 
rator to  observe  how  his  tube  is  working.  The  picture  could  be  taken  in 
bright  daylight ;  the  envelopes  will  protect  the  plate  against  all  light  ex- 
cept the  X-rays. 

When  the  switch  is  turned  on  and  the  X-rays  produced,  they,  the 
rays,  shine  down  on  the  plate  penetrating  the  paper  of  the  envelopes  as 
though  the  plate  were  not  covered  at  all.  The  rays  penetrate  the  hand 
also  and  act  upon  the  plate  beneath.  They  penetrate  the  bones  of  the 
hand  less  readily  than  the  flesh,  and  hence  there  is  less  action  on  the 
plate  directly  beneath  the  bones.  In  other  words,  there  is  a  shadow  of 
the  hand  thrown  on  the  plate,  the  shadow  of  the  bones  being  denser  than 
the  shadow  of  the  flesh.  The  shadow  of  the  flesh,  in  fact,  may  be  so 
light  that  it  is  scarcely  discernible,  or  even  entirely  blotted  out.  This  is 
the  case  when  a  very  high  tube  is  used  and  a  long  exposure  made. 

The  length  of  time  of  the  exposure  of  the  plate 
Duration  Of  to  the  action  of  the  X-rays  when  making  a  radio- 

Exposure,  graph  depends  on  several  things.     (1)  The  miiliam- 

perage  sent  through,  the  tube.  Other  factors  re- 
maining the  same,  the  more  milliamperage  sent  through  the  tube  the 
shorter  the  exposure  necessary,  because  the  higher  the  milliamperage 
sent  through  the  tube  the  greater  the  numBer  of  X-rays  produced. 
A  coil  equipped  with  a  milliamperemeter  enables  the  operator  to 
observe  the  exact  number  of  milliamperes  passing  through  the  tube. 
(2)  The  nature  of  the  X-rays.  Other  factors  remaining  the  same, 
the  more  penetrating  the  X-rays  the  shorter  the  exposure  necessary. 
The  higher  the  vacuum  of  the  tube  up  to  a  given  point,  the  more 
penetrating  the  rays  from  it.  A  low  tube  is  useless  for  radiographic 
work.  (3)  The  distance  of  the  plate  from  the  tube.  Other  factors 
remaining  the  same,  the  shorter  the  distance  between  the  plate  and 
the  tube  the  shorter  the  exposure  necessary.  (4)  The  thickness  of  the 
part  to  be  radiographed.  Other  factors  remaining  the  same,  the  thicker 
the  part  the  longer  the  exposure  necessary.     (5)  The  density  of  the  part 


7-' 


ELEMENTARY   RADIOGRAPHY 


to  be  radiographed.  Other  factors  remaining-  the  same,  the  denser  the 
part  the  longer  the  exposure  necessary.  (6)  The  sensitiveness  of  the 
plate.  Other  factors  remaining  the  same,  the  more  sensitive  the  plate 
the  shorter  the  exposure  necessary.  The  product  of  some  manufacturers 
is  more  sensitive  than  others.  As  a  plate  or  film  grows  old  it  becomes 
less  sensitive,  finally  becoming  entirely  useless. 


Fig.  71.     Radiograph  of  the  hand,  made  from  a  post-  similar  to  Fig.  To.     (Reduced  one-half.) 


It  will  be  seen  from  the  foregoing  that  so  many  things  enter  in  for 
consideration  that  the  exact  time  of  exposure  cannot  be  stated  with  any 
degree  of  clearness.  Elaborate  systems  of  calculation  have  been  worked 
out  so  that  if  the  distance  of  the  tube  from  the  plate,  the  penetration  of 
the  X-rays  measured  with  a  penetrometer,  the  milliamperage  sent  through 
the  tube,  and  the  thickness  of  the  part  be  known,  reference  can  be  made 
to  a  printed  table  and  the  exact  time  of  exposure  necessary  learned. 
While  commending  such  work  as  efforts  along  the  right  line,  I  consider 
them  failures  so  far  as  practical  application  in  dental  work  is  concerned. 
Notice  that  in  the  calculate  n  the  density  of  the  pari  and  sensitiveness  of 
the  plate  are  not  taken  into  account  at  all. 


M.IK  IXC  RADIOGRAPHS  7$ 

Each  man  must  learn  to  properly  time  his  exposure  by  personal  ex- 
perimentation. This  statement  is  likely  to  be  contradicted  by  those  who 
construe  it  to  mean  that  no  idea  at  all  of  the  time  of  the  exposure  can  be 
learned  except  by  experiment.  That  is  not  what  I  am  saying,  however. 
The  idea  1  wish  to  convey  is  that  these  tables  of  calculation,  on  the  time 
of  exposure,  give  only  the  approximate  length  of  time  of  exposure  neces- 
sary, and  that  a  very  little  experience  and  the  use  of  judgment  render 
them  useless.  They  are  always  useless  except  when  a  penetrometer  is 
used  and  the  coil  is  equipped  with  a  milliamperemeter. 


2.     Trays  for   developing  and   fixing  solutions. 


To  make  the  negative  (the  picture  on  the  glass  of  the  plate)  of  the 
radiograph  shown  in  Fig.  71,  the  factors  were  as  follows: 

1.  Machines  used — an  18-inch  induction  coil,  with  a  two-point  elec- 
trolytic interrupter,  operating  on  no-volt,  D.  C.  circuit.  All  resistance 
of  rheostat  cut  out. 

2.  Strength  of  current.  Machine  not  equipped  with  amperemeter 
or  milliamperemeter.  Approximate  amperage  of  the  primary  current, 
26.  Secondary  current  sufficiently  powerful  to  obtain  a  fat.  fuzzy  spark 
10  inches  long. 

3.  Penetration  of  X-rays.  Tube  backs  »up  7  inches  of  parallel 
spark.  Distances  of  tube  regulating  spark  gap  4  inches.  Therefore,  the 
tube  is  high  and  the  rays  from  it  quite  penetrating  when  it  is  properly 
lighted. 

4.  Distance  of  target  from  plate.     Seventeen  (17)   inches. 

5.  Thickness  of  part.  That  of  the  hand,  about  1^2  inches  at  thick- 
est part. 

6.  Density  of  part.     That  of  hand. 

7.  Plate  used.  Lumiere  special  X-ray  plate.  (An  ordinary  plate 
might  have  been  used  to  take  such  a  picture.) 

8.  Time  of  exposure  of  plate  to  action  of  rays.     Five  seconds. 

9.  Time  plate  remained  in  developer.     Two  and  one-half  minutes. 
It  should  always  be  the  effort  of  the  operator  to  make  the  exposure 


74  ELEMENTARY  RADIOGRAPHY 

as  short  as  possible  (though  it  was  not  done  in  this  instance),  so  that 
the  patient  may  not  be  unnecessarily  exposed  to  the  X-rays.  So  far  as 
overexposure  of  the  plate  itself  is  concerned,  however,  we,  in  dental 
work,  need  not  fear  it  much.  If  we  expose  the  plate  unnecessarily  long 
we  may  correct  our  mistake  by  leaving  it  in  the  developing  solution  a 
shorter  length  of  time. 

During  exposure,  the  patient,  tube  and  plate  must  be  perfectly  im- 
mobile.    After  the  exposure  we  are  ready  to  "develop  the  negative." 

Remove  the  plate  from  the  envelope  in  the  dark 

method  Of  room,  exposing  it  only  to  the  ruby  light.     It  has  not 

Development.  changed  in  appearance  at  all.     It  still  looks  like  a 

piece  of  translucent,  white  glass.  But  the  picture  is 
there.     It  needs  only  to  be  developed. 

This  is  done  by  immersing  the  plate,  sensitive  side  up,  in  an  aqueous 
solution  of  chemicals,  the  developer.  This  developer  oxidizes  the  silver 
which  has  been  acted  upon  by  the  X-rays,  but  does  not  oxidize  the  silver 
which  lias  not  been  acted  upon  by  the  X-rays. 

Place  the  plate  in  the  tray  (Fig.  72)  containing  the  developer  with 
the  film  side  up,  quickly  covering  the  plate  with  the  solution.  It  is  better 
to  begin  development  in  absolute  darkness,  not  turning  on  the  lantern 
till  needed  for  first  examination  of  the  plate,  and  even  then  using  as  little 
light  as  possible.  A  dark  room  lantern  may  be  comparatively  safe,  but 
when  handling  very  sensitive  plates  no  light  at  all  is  safer  still.  Many 
properly  exposed  plates  have  been  "fogged"  in  the  "dark"  room.  Trays 
can  be  purchased  from  any  photographic  supply  house.  Always  use  a  tray 
sufficiently  large  to  easily  receive  the  plate.  The  action  of  the  developer 
will  be  hastened  and  made  more  uniformly  perfect  by  slightly  raising  then 
lowering  one  end  of  the  tray,  and  so  moving  the  developer  over  the  sur- 
face of  the  plate. 

The  length  of  time  it  takes  the  image  to  "come  up"  or  show  varies 
according  to  the  length  of  exposure.  The  shorter  the  exposure  the  longer 
the  plate  must  remain  in  the  developer.  For  example,  when  the  negative 
of  Fig.  71  was  made  three  others  were  made,  all  the  factors  remaining 
the  same — same  machine,  same  strength  current,  and  so  on — except  the 
time  of  exposure  and  the  time  the  plate  was  left  in  the  developer.  One 
plate  was  exposed  2T/2  seconds,  and  was  left  in  the  developer  five  minutes; 
another  was  exposed  10  seconds  and  left  in  the  developer  two  minutes, 
and  another  was  exposed  30  seconds  and  left  in  the  developer  iy2 
minutes.  The  four  finished  negatives  are  so  nearly  alike  that  they  can 
scarcely  be  distinguished  one  from  the  other. 

Developing  is  not  completed  as  soon  as  the  image  shows.     Sometimes 


MAKING  RADIOGRAPHS  75 

the  image  can  be  seen  better  by  removing  the  plate  from  the  developer 
and  holding  it  up  to  the  ruby  light.  If  the  exposure  has  been  well  timed 
the  "high  lights"  will  commence  to  appear  (i.e.,  the  plate  will  begin  to 
turn  dark  in  places)  in  about  15  seconds,  and  the  image  can  be  seen 
tolerably  well  in  30  seconds.  If  this  is  the  case  the  plate  should  be 
left  in  the  developer  about  5  minutes.  From  the  foregoing  we  may  make 
the  following  rule :  Leave  the  plate  in  the  developer  about  20  times  as 
long  as  it  takes  for  the  high  lights  to  appear,  or  10  times  as  long  as  it 
takes  for  the  image  to  appear.  This  is  not  an  inflexible  rule.  Indeed, 
no  inflexible  general  rule  can  be  made,  because  of  the  difference  in  the 
action  of  different  developers.  Another  rule  is  to  leave  the  plate  in  the 
developer  until  the  image  is  about  lost — and  the  plate  seems  almost  black. 

The  actual  time  of  developing  will  vary;  2  or  3  minutes  for  over- 
exposed plates ;  about  5  minutes  for  plates  which  have  been  well  ex- 
posed;    15  to  40  minutes  for  under-exposed  plates. 

There  are  a  very  great  many  different  developing  formulas,  any  one 
of  which  may  be  used.  In  making  up  developers,  chemicals  should  in- 
variably be  dissolved  in  the  order  as  named.  The  following  are  some  of 
the  most  popular  developer  formulas : 

M — Q  Developer  * 

Avoirdupois       Metric  System 

Water    10  ounces  =  300 

Metol  7  grains  =. 

Hydrochinon    30  grains  = 

Sulphite  of  Soda  (desiccated) no  grains  = 

Carbonate  of  Soda  (desiccated) 200  grains  = 

10  per  cent,  solution  Bromide  Potassium 40  drops    = 

Hydrochinon   Developer 
No.   1 

Avoirdupois  Metric  System 

Hydrochinon    300  grains 20  grammes 

Sulphite  of  Soda 6  ounces 180  grammes 

Water    48  ounces 1,440  c.c. 

No.  2 

Carbonate  of   Potassium 4  ounces 120  grammes 

Water   t>2  ounces 960  c.c. 

To    Develop,   take 
No.    1,  6  ounces    (180  c.c.)  ;    No.  2,  4  ounces    (120  c.c.)  ;     10  per  cent,   solution 
Bromide  of  Potassium,  3  to  10  drops.     Mix  the  developers  in  the  order  given, 
and  use  cold. 


500 

c.c. 

IV2 

grammes 

2 

grammes 

7 

grammes 

13 
40 

grammes 
drops 

*M — Q  stands  for  "metal — quinol."  In  photography  the  word  "quinol"  is  used 
as  an  abbreviation  for  "hydroquinol."  This  is  unfortunate,  because  quinol  and 
hydroquinol  are  different  substances.  There  are  several  words  and  different  spell- 
ings of  the  same  word  used  to  designate  the  substance — hydroquinol.  They  are : 
hydroquinon  (spelled  also  hydroquinone)  ;  hydrochinol  (spelled  also  hydrokinol)  ; 
hydrochinon   (spelled  also  hydrochinone,  hydrokinon,  and  hydrokinone). 


76  ELEMENTARY  RADIOGRAPHY 

Pyro   Developing   Formula 
Pyrogallic  Acid  Solution 

"A"  Avoirdupois  Metric  System 

Pyrogallic   Acid    i  ounce     30  grammes 

Sulphuric  Acid    20  minims I  c.c. 

Water  28  ounces    840  c.c. 

Soda  Solution 

iidh 

Avoirdupois  Metric  System 

*Carbonate  of  Soda  (Anhydrous) 2  ounces 60  grammes 

*Sulphite  of  Soda   (Anhydrous) 3  ounces 90  grammes 

Water   28  ounces 840  c.c. 

To  Develop,  take 
"A."  1  ounce  (30  c.c.)  ;    "B,"  1  ounce  (30  c.c.)  ;    Water,  8  ounces  (240  c.c).     This 
developer  will  then  contain  1.56  grains  Pyro  per  ounce. 

The  developer  may  be  made  and  kept  in  stock  solutions  as  above,  if 
desired.  A  better  plan  is  to  buy  the  prepared  developing  powders.  They 
may  be  purchased  at  any  photographic  supply  store.  The  chemicals  come 
in  glass  tubes  or  packages  mixed  in  the  proper  proportions,  and  all  that 
is  necessary  to  make  the  solution  is  to  dissolve  them  in  the  quantity  of 
water  (distilled  or  tap  water  either)  suggested  on  the  package.  The 
package  or  tube  usually  contains  a  sufficient  quantity  to  make  4  to  8 
ounces  of  developing  solution.  The  advantages  of  this  over  mixing  the 
chemicals  yourself  are :  First,  the  convenience  and  saving  of  time,  and 
second,  only  small  quantities  being  made  at  one  time,  the  developer  is 
used  immediately,  and  is  therefore  always  fresh  when  used. 

A  developing  bath  does  not  keep  well  in  stock  solution  unless  the 
bottles  are  full  and  well  corked.  Even  then  discoloration  and  disintegra- 
tion occur  in  the  course  of  a  month  or  so.  It  is  always  advisable  to  use 
as  fresh  a  solution  as  possible.  Packed  in  the  box  with  the  plates  will 
always  be  found  a  formula  for  a  developer  recommended  by  the  manu- 
facturer of  the  plates.  It  is  not  at  all  necessary  to  use  the  particular 
developer  recommended. 

During  the  hot  summer  months  it  is  necessary 

temperature.  to  use  ice  in  the  developer,  ice  water  to  make  the 

solution,  or  place  the  tray  containing  the  developer 
in  another  larger  tray  with  ice  water  in  it.  If  the  developer  is  too  warm 
it  will  soften  the  emulsion,  cause  frilling  at  the  edges,  blistering  and 
fogging  of  the  negative.  The  developer  should  be  between  60  and  75 
degrees  F.  It"  too  cold,  development  takes  place  slowly,  and  the  negative, 
when  finished,  is  pale  and  thin.  I  use  tap  water  in  the  winter  and  have 
no  trouble  due  to  improper  temperature.  In  the  summer,  though,  even 
using  ice  water  and  ice,  the  work  is  often  discouraging.  If  possible  dur- 
ing the  hottest  weather  defer  development  until  the  cool  of  the  evening. 


*If  crystal^   arc   used,   double  the  quantity. 


MAKING  RADIOGRAPHS 


77 


When    development    is    complete,    remove    the 
fixing.  plate,  dip  it  in  clear  water,  then  immerse  it  in  the 

fixing  bath.  The  fixing  bath  is  a  solution  of  chem- 
icals which  dissolves  out  the  unaffected  silver.  Leave  the  plate  in  the 
fixer  for  two  or  three  minutes  after  the  milky  appearance  of  the  glass 
side  of  the  plate  has  disappeared.  A  plate  must  be  removed  promptly 
from  the  developer  as  soon  as  development  is  complete,  or  the  negative 
will  be  overdeveloped,  spoiled,  but  it  may  be  left  in  the  fixing  bath  for 
hours  longer  than  necessary  without  danger  of  spoiling  the  negative. 


Fig.   73.      Titubator. 


It  will  not  injure  the  plate  to  remove  and  replace  it  in  the  baths  at 
any  time  during  developing  or  fixing. 

The  actual  time  required  for  fixing  varies  from  5  to  20  or  30  min- 
utes. The  thicker  the  emulsion  the  longer  time  it  requires  for  fixing. 
Movement  of  the  fixing  solution  over  the  surface  of  the  plate  will  hasten 


78  ELEMENTARY  RADIOGRAPHY 

fixing.  A  titubator  (Fig.  y^  ls  a  machine  on  which  the  fixing  bath  tray 
may  be  set,  and  the  bath  kept  in  constant  movement  over  the  plate. 

When  several  negatives  are  being  made  at  the  same  time,  it  is  well 
to  n>e  a  fixing  box  (Fig.  74)  instead  of  a  tray.  If  the  plates  were  piled 
one  on  another  in  the  tray,  they  would  probably  stick  to  one  another  and, 
when  pulled  apart,  the  emulsion  would  be  scarred.  The  plates  stand  on 
end  in  the  fixing  box,  fitting  into  grooves. 

Hyposulphite  of  soda  is  the  standard  fixer.  There  are  not  a  great 
number  of  fixers,  as  there  are  of  developers,  to  choose  from.  Hypo- 
sulphite of  soda  and  water  alone  will  fix  plates,  but  is  not  so  efficacious 
as  when  other  chemicals  are  added  to  harden  the  emulsion. 

Acid-Fixixg  Bath 

Avoirdupois  Metric  System 

Water   (34       ounces  2  liters 

Hyposulphite  of   Soda 1<5       ounces  450  grammes 

Sulphite  of  Soda    ( Anhydrous) 24  ounce  20  grammes 

When  fully  dissolved,  add  the  following  hardener : 

Powdered   Alum    Y2  ounce  15  grammes 

Citric   Acid    V2  ounce  15  grammes 

A  -tock  solution  may  be  made  as  given  in  the  foregoing  formula,  or 
the  prepared  fixing  powder  purchased,  and  the  fixing  bath  made  by  sim- 
ply dissolving  the  powder  in  a  stated  quantity  of  water.  There  is  nothing 
secret  about  the  formulas  of  the  prepared  fixing  powders.  They  are  all 
practically  the  same  as  the  formula  given.  The  advantage  in  using  them 
lies  in  the  saving  of  time  and  energy  that  would  otherwise  be  spent 
weighing  chemicals.  If  prepared  developing  and  fixing  powders  are  used, 
it  will  not  be  necessary  to  have  a  pair  of  scales  for  this  work.  A  grad- 
uated glass  for  measuring  liquids  will  be  all  that  is  needed.  During  the 
hot  months,  it  is  expedient — not  necessary — to  use  a  freshly  mixed  fixer. 
If  this  is  done  the  negative  is  less  likely  to  frill  or  blister.  Unlike  the 
developing  bath,  however,  the  fixing  bath  will  keep  without  disintegra- 
tion for  months.  If  scum  or  sediment  appears  after  standing  for  some 
time,  this  may  be  removed  by  filtering  the  solution  through  filter  paper 
or  cotton. 

The  temperature  of  the  fixer  should  he  at  least  as  low  as  that  of  the 
developer,  and  better  lower.  sa\  about  50  degrees  I'. 

When  fixed,  if  the  plate  is  held  up  to  the  light  (any  light  for  the 
plate  i-  no  longer  sensitive  to  light),  the  shadow  of  the  bones  of  the  hand 
will  appear  as  transparencies;  the  flesh  shows  a  little  less  transparent 
than  the  hone,  and  the  balance  of  the  plate  will  he  opaque  and  black. 
Thus  the  shadows  show  1  i j^l it .  and  where  no  shadow  was  thrown  the  plate 
i-  dark.  Hence  the  name  negative  which  is  applied  to  this  picture  on 
the  plate.    The  making  of  the  positive  picture  on  paper,  the  print,  as  h 


MAK1XG  RADIOGRAPHS 


79 


is  usually  called,  from  the  negative  will  be  described  presently.  The 
plate  is  no  longer  sensitive  to  white  light,  and  may  therefore  be  exposed 
to  it  any  time  after  having  been  in  the  fixer  a  minute  or  so. 

Great  care  must  be  exercised  not  to  get  any  of  the  fixing  bath  into 
the  developer.  A  very  little  "hypo"  will  spoil  the  developer.  It  is  well 
to  label  the  trays  so  that  the  tray  used  to  hold  the  fixer  one  time  will  not 
be  used  for  the  developer  another.  Or.  instead  of  labeling  the  trays,  a 
black  one  may  bt  used  for  the  developer  and  a  white  tray  for  the  fixer. 


Fig.    74.     Fixing    box. 


Fig.    75.     Plate,    or    negative,    rack. 


When  fixing  is  completed  the  negative  must  be 
UlasMng.  washed  in  clear  water  to  remove  all  '"hypo"  from  it. 

If  the  negative  be  placed  in  a  tray,  the  tray  in  a 
basin  or  sink  and  the  tap  turned  up.  or.  in  other,  words,  if  the  negative 
be  washed  in  running  water  it  requires  15  to  30  minutes  to  thoroughly 
wash  it.  Where  running  water  cannot  be  had.*  and  sometimes  during 
hot  weather  when  tap  water  is  too  warm,  the  negative  may  be  placed  in 
a  larger  vessel  of  water  and  left  for  about  an  hour,  changing  water  sev- 
eral times.  A  tray  of  water  used  on  a  titubator  is  efficient.  The  water 
must  be  changed  often,  and  the  time  required  is  about  three-quarters  of 
an  hour  or  longer.  When  several  negatives  are  being  made,  it  is  ad- 
visable to  use  a  washing  box  similar  to  the  fixing  box.      (  Fig.  74.) 


*  "Running  water*'  is  much  to  be  preferred,  as  the  friction  or  movement  of 
the  water  is  a  great  factor  in  cleansing  the  plate.  After  a  few  months,  if  plates 
show  cloudiness,  or  a  metallic  luster  is  observed,  this  means  that  the  plates  were 
not  thoroughly  washed.  It  is  even  advisable,  after  washing,  to  rub  the  surface  of 
the  film  side  with  clean,  wet  cotton,  holding  the  plate  under  a  faucet  during  the  act. 


8.) 


ELEMENTARY  RADIOGRAPHY 


The  next   and  the  last  step  in  the  making  of  the 
Drying.  negative,  is  to  dry  it.     The  plate  should  be  set  on 

edge.  Drying  should  take  place  in  a  clean  atmos- 
phere, so  that  no  dust  or  soot  will  fall  on  and  stick  to  the  coated  surface 
of  the  negative.  Plate  racks  (Fig.  j=> )  may  be  used,  but  are  not  a  neces- 
sity. The  plate  may  he  set  on  edge  at  an  angle  of  about  95  degrees  by 
simply  leaning  it  up  against  some  perpendicular  wall.     (  Fig.  j6. )     Dry- 


Fig.    70.     Negatives    leaning   against    perpendicular    wall,    drying. 


ing  requires  several  hours.  It  may  he  hastened  by  placing  the  negative 
in  a  breeze.  By  immersing  the  negative  in  a  mixture  of  formalin  and 
alcohol,  then  placing  it  in  the  breeze  of  an  electric  fan.  drying  will  be 
very  materially  hastened.  The  use  of  the  formalin  and  alcohol  some- 
time- causes  spotting  and  blurring  of  the  negative.  If  all  the  salts  "t 
the  fixer  are  not  well  washed  out  of  the  emulsion,  it  will  not  dry  prompt- 
ly, but  will  become  rough  and  sticky,  and.  when  finally  dry.  it  will  be  fill! 
of  little  holes. 

Summarizing  the  making  of  the  negative,  it  consists  of  exposing 
developing  ( washing — mere  dipping  in  water),  fixing,  washing,  and  dry- 
ing. 

If  tlie  negative  when  finished  i-  very  dark.  SO  dark  that  parts  of  the 
image  are  lost,  the  plate  was  either  overexposed,  or  overdeveloped,  or 


MAKING  RADIOGRAPHS  81 

both.  I  prefer  usually  to  say  that  it  was  overdeveloped,  for  even  if  it  had 
been  exposed  unnecessarily  long,  this  mistake  might  have  been  corrected 
by  leaving  it  in  the  developer  a  shorter  length  of  time.  If  the  negative 
is  almost  entirely  transparent  and  the  image  can  hardly  be  seen,  it  is  due 
to  underexposure,  or  underdevelopment,  or  both. 

The   mistake   of   overexposure   or   overdevelop- 
RcdUCCrS.  ment  can  be  corrected  to  an  extent  by  the  use  of  a 

"reducer." 
The   following  solution  is  a  reducer: 

*A.  Water    16  ounces  (480  c.c.) 

Hyposulphite  of  Soda 1  ounce  (30  grammes) 

B.  Water 16  ounces  (480  c.c.) 

Potassium  Ferricyanide  1  ounce  (30  grammes) 

Mix  8  parts  of  solution  "A"  and  one  part  of  solution  "B,"  and  use  in  subdued 

light. 

The  negative  can  be  placed  in  this  solution  directly  after  fixing, 
without  washing.  Or  it  may  be  washed- — it  makes  little  or  no  difference. 
If  a  dry  negative  is  to  be  reduced,  it  must  be  soaked  in  water  for  at  least 
half  an  hour  before  placing  it  in  the  reducer.  When  sufficiently  reduced, 
wash  thoroughly  for  about  three-quarters  of  an  hour,  then  dry.  The 
work  of  reducing  may  be  done  in  any  light. 

When  not  in  use  keep  solution  "B"  protected  from  the  action  of 
light.  Remember  that  this  solution  is  one  of  the  most  powerful  poisons 
known.     Handle  it  with  extreme  caution. 

The  mistake   of  underexposure   cannot  be  cor- 

Tntcnsifier.  rected  to  an  appreciable  extent  by  any  means. 

The    mistake   of   an    underdevelopment    can    be 
corrected  to  an  extent  by  the  use  of  an  "intensifier." 

After  having  fixed  the  negative,  wash  it  well  in  running  water  for 

about  thirty  minutes  or  longer,  then  place  in  the,  following  solution : 

Mercuric    Bichloride    200       grains      (13.3  grammes) 

Potassium  Bromide    120       grains        (S.O  grammes) 

Water     §y2  ounces     (195  c.c.) 

Keep  the  plate  in  this  solution  a  short  time,  when  it  will  be  observed 

to  be  bleached  uniformly  white  (the  longer  the  negative  is  bleached  the 

denser  it  will  ultimately  become).     Remove  from  the  bleaching  solution. 

wash  in  running  water  for  a  few  minutes,  then  blacken  in  the  following 

solution  : 

Sodium    Sulphite    1  ounce       (30  grammes) 

Water  4  ounces   (120  grammes ) 

Or 

Ammonia     20  minims     (1  c.c.) 

Wrater  1  ounce 

*  "Electro-Therapeutics  and  Roentgen  Rays,"  Kassaban. 


$2 


ELEMENTARY  RADIOGRAPHY 


It  is  now  being  blackened,  tbe  negative  is  again  washed,  then  dried. 
Intensifying  should  be  done  in  a  subdued  light — not  in  bright  daylight. 

An  old  negative,  one  which  has  been  made  for  some  time,  may  be 
intensified  by  first  soaking  in  water,  then  following  the  technic  given. 

Prepared  reducers  and  intensifiers,  with  directions  for  their  use,  may 
be  purchased  at  any  photographic  supply  house. 


Fig.    77.      Showing   how    the    printing   frame    is    held    Up    to    the    light    to    expose    the    photographic 
paper.     Also  showing  the  back   of  the  printing  frame,   the   frame   half   open,  and  the   photographic 

paper    in    position. 


While  reducers  and  intensifiers  have  their  place  in  dental  radiog- 
raphy, they  are  used  only  to  correct  mistakes,  and  they  do  not  entirely 
correct  the  mistakes.  It  is  usually  expedient  to  make  a  new  negative 
ratber  than  to  attempt  to  reduce  or  intensify  a  faulty  one. 

Round  transparent  spots  on  the  negative  are  caused  by  air  bubbles, 
or  air  "bells,"  as  they  are  called,  attaching  themselves  to  the  emulsion 
side  of  the  plate  while  in  the  developer. 

Spots  of  irregular  size  and  character  appearing  on  a  negative  are 
due  often  to  the  use  of  an  old  developer.  In  radiographic  work,  where 
the  appearance  of  a  spot  may  determine  a  diagnosis,  it  is  to  be  hoped  that 
fresh  developer  will  always  be  used.  By  fresh  developer  I  mean  de- 
veloper not,  at  most,  over  a  month  or  so  old,  having  been  kept  while  in 
Stock  in  a  filled,  tightly  stoppered  bottle,  and  free  from  all  scum  rind 
sediment.  A  developer  containing  pyrogallic  acid  disintegrates  so  rap- 
idly that  it  must  be  used  immediately  after  mixing — it  will  not  keep  at 
all.     "Pyro"  developers  stain  the  hands  badly. 


MAKING  RADIOGRAPHS  83 

When  the  negative  is  dry  we  are  ready  to  make 
Pwittoe  the   positive   pictures.     The   pictures  are   made   on 

Prints,  sensitized  paper,  a  very  fine  grade  of  white  paper, 

one  side  of  which  is  coated  with  a  silver  salt  some- 
what as  plates  and  films  are  coated.  These  papers  sell  under  such  vari- 
ous names  as  Velox,  Cyko.  Artura,  and  Azo,  and  may  be  purchased  in 
any  size,  put  up  in  light-proof  packages.  Papers  are  not  as  sensitive  as 
plates  and  films,  and  an  orange  instead  of  a  ruby  light  may  be  used  in 
the  dark  room. 

Place  the  negative,  emulsion  side  up,  in  the  printing  frame  (Fig.  Jj). 
Place  a  sheet  of  paper,  sensitive  side  down,  over  the  negative,  and  close 
printing  frame.  The  sensitive  side  of  the  paper  may  be  determined  by 
observing  that  the  paper  curls  slightly  toward  it ;  or  by  biting  a  cornet 
of  the  paper,  when  the  sensitive  side  will  stick  slightly  to  the  teeth. 

To  make  the  exposure  now,  either  artificial  or  daylight  may  be  util- 
ized. Before  making  the  exposure  be  sure  that  the  balance  of  the  paper 
in  the  package  is  well  protected  against  the  light.  Hold  the  printing  frame 
so  the  light  will  shine  through  the  negative  and  strike  the  paper.  (Fig. 
J  J.)  It  is  not  necessary  to  hold  the  printing  frame  immovable  during 
exposure.  The  time  of  exposure  varies  greatly  according  to  the  density 
of  the  negative ;  the  denser  the  negative  the  longer  the  exposure  must  be. 
Some  idea  of  the  time  of  exposure  necessary  may  be  learned  from  the 
directions  enclosed  with  the  paper.  To  make  the  print  for  Fig.  71,  a 
16  c.p.  electric  light  was  used,  holding  the  printing  frame  about  8  inches 
from  the  light  and  exposing  the  paper — Azo — 3  minutes. 

With  the  16  c.p.  light  turned  off,  in  the  orange 

Development  light,  the  paper  is  now  removed  from  the  frame.    As 

Of  Prints,  with  the  plate  there  is  not  the,  slightest  change  in  the 

appearance  of  the  paper  after  exposure,  but  the 
image  is  there,  it  is  latent,  it  needs  only  to  be  developed. 

The  developing  formulae  for  papers  are,  broadly  speaking,  the  same 
as  for  plates.  It  is  very  important  that  the  developer  for  paper  be  freshly 
mixed,  for  the  slightest  discoloration  of  the  bath  will  soil  the  paper.  It 
is  not  desirable  to  save  the  developer  used  to  make  the  negative  and  use 
it  again  for  the  paper.  It  is  too  liable  to  cause  discoloration  of  the  print. 
"Pyro"  is  a  very  poor  developer  for  paper. 

Immerse  the  paper  quickly,  sensitive  side  up,  gently  passing  the  tips 
of  the  fingers  over  the  surface,  to  hasten  development  by  agitating  the 
developer,  and  to  keep  the  paper  submerged.  As  soon  as  the  image  ap- 
pears as  desired,  transfer  it  to  clean  water,  then  quickly  into  the  fixeiv 
(It  is  kept  in  the  water  but  a  moment  or  so.)  If,  when  placed  in  the 
developer,  the  image  comes  up  so  quickly  that  it  gets  too  dark  before  it 


s:  ELEMENTARY  RADIOGRAPHY 

can  be  transferred  to  water  and  fixer,  it  has  probably  been  overexposed. 
Shorten  the  time  of  exposure,  and  if  the  image  still  comes  up  too  quickly, 
dilute  the  developer.  It  the  whites  of  the  prints  come  up  gray,  add  a 
few  drops  of  a  to  per  cent,  solution  of  bromide  of  potassium  to  the 
developer. 

Any  number  of  prints — pictures — may  be  made  from  a  negative. 

The  fixing  bath  for  prints  is  the  same  as  for  plates,  but  the  bath 
used  to  make  the  negative  should  not  be  saved  and  used  again  for  prints. 
It   might   discolor   them. 

Allow  prints  to  remain  in  the  fixer  15  to  20  minutes.  This  dissolves 
out  the  unaffected  silver. 

Next  wash  print  in  running  water  for  an  hour.  No  visible  change 
occurs  in  the  print  from  the  time  it  leaves  the  developer.  Fixing  and 
washing  are  done  to  make  it  permanent.  The  temperature  of  the  de- 
veloper, fixer,  and  water  should  be  the  same  as  for  plates,  to' obtain  the 
best   results. 

When  thoroughly  washed  remove  the  prints  from  the  wash  water 
and  place  on  a  piece  of  clean  glass  face  down  one  on  the  other,  and 
press  out  the  water.  Then  lay  them  out  separately  on  a  frame,  covered 
with  cheese  cloth.  The  cheese  cloth  being  very  thin,  allows  the  prints 
t>:  dry  on  the  side  next  the  cloth  as  well  as  the  upper  side. 

When  dry  the  prints  may  he  mounted  on  cardboard. 


Dental  Radiography. 

CHAPTER  V. 
making  Dental  Radiographs. 

In  the  foregoing  chapter  we  dealt  with  the  general  elementary  prin- 
ciples of  radiography.  We  shall  now  take  up  a  more  concrete  considera- 
tion of  dental  radiography. 

The  first  radiograph  of  the  teeth  was  exhibited  by  Prof.  K 
to  the  Society  of  Physics  at  Frankfort-on-Main.  Germany,  in  February, 
189(3 — only  a  few  months  after  the  discovery  of  the  X-ray.  Five  months 
later  an  article  appeared  in  Dental  Cosmos  by  Morton,  entitled  "X-Rays 
in  Dentistry."  Since  then  there  have  been  scores  of  articles  written  on 
the  subject  and  published  in  various  dental,  medical,  and  Roentgeno- 
graphic  journals. 

Most  dental  radiographs  are  made  on  films  held  in  the  mouth  dur- 
ing their  exposure  to  the  X-rays,  the  patient  being  seated  in  the  dental 
chair.    Ordinary  films,  as  stated  in  Chapter  IV,  are  not  efficacious. 

As  stated  previously,  but  two  manufacturers,  the 

Spec)  Hford    Co.    and    the    Eastman    Co..    supply    special 

XRay  films.  FF  3     F 

X-ray  films. 

The  Ilford  film,  being  a  foreign  product,  cannot  be  delivered  with 
desired  promptness.  It  is.  however,  the  best  X-ray  film  on  the  market, 
and  may  be  obtained  from  the  American  agent  for  Ilford  goods,  E.  B. 
Meyrowitz,  104  West  23d  St..  Xew  York  City.  Ilford  films  of  prac- 
tically any  size — 4x5  in.,  jxj  in.,  Sxio  in.,  etc. — can  be  purchased  in 
packages,  one  dozen  films  to  the  package. 

Ilford  films  are  also  supplied  just  ready  for  dental  use  in  sizes  of 
about  i3sxi?s  in-,  one  film  to  the  packet,  wrapped  in  black  paper  and 
covered  with  a  rubber-like,  moisture-proof  material,  such  as  tailors  use  to- 
mend  clothes. 

For  the  past  several  years  the  Eastman  Kodak  Mfg.  Co.,  of  Roches- 
ter, X.  Y.,  have  supplied  films  for  radiographic  work.  These  films  are 
covered  with  the  same  emulsion  that  is  used  to  make  cinematograph 
(  moving  picture)  films.  There  are  two  kinds  of  cinematograph  films, 
the  positive  and  the  negative.  The  positive  films  yield  very  satisfactory 
radiographic  results,  but  the  negative  films  are  little  or  no  better  than 

85 


86  DENTAL    RADIOGRAPHY 

ordinary  films  for  cameras.  This  explains  why  some  of  the  films  hereto- 
fore supplied  by  the  Eastman  Company  have  proved  satisfactory,  while 
others  have  not,  for  both  the  negative  and  positive  films  have  been  sold 
under  the  label  "X-ray  films."  I  have  been  in  communication  with  the 
Eastman  Kodak  Mfg.  Co.,  and  have  informed  them  of  the  failure  of 
their  negative  cinematograph  films  to  meet  the  requirements  of  a  good 
X-ray  film,  but  to  guard  against  a  possible  mistake  it  would  be  well  when 
ordering  to  state  that  the  positive  film  is  wanted.  The  negative  film  is 
a  little  faster  than  the  positive,  but  sufficiently  contrasty  results  cannot 
be  obtained  with  it. 


0       E.  1 


Fig.   78.      A.   rubber-dam  stretched  out  and  fastened  to  a  board  with  pins.     B,  the  rubber  covered 

with   cement  and   the  film   packet  on   it.     C,  pins  removed   from   one  end  and  the   rubber  lapped 

over    packet.      D,   all    pins   removed.      E,    excess    rubber    trimmed    off. 


The  Eastman  Company  will  supply  films  in  any  size  to  order;  or 
in  little  black  paper  packets,  ready  for  dental  use,  two  films  about  i^xi^ 
in.,  to  the  packet,  the  sensitive  side  of  the  films  presenting  toward  the 
black  side  of  the  packet. 

The  special  4x5  in.  X-ray  film,  formerly  manufactured  by  the  Seed 
Dry  Plate  Mfg.  Co.,  of  St.  Louis,  is  now  made  by  the  Eastman  Kodak 
Co.,  of  Rochester,  successors  of  the  Seed  Dry  Plate  Co.  The  old  Seed 
film  was  not  a  non-curling  film.  The  "Seed  Positive  Film."  now  manu- 
factured by  the  Eastman  Co.,  however,  has  a  coating  of  gelatin  on  the 
back  of  the  film  to  keep  it  from  curling.  With  the  film  thus  coated  on 
both  sides  it  is  impossible  to  tell  by  observation  which  is  the  sensitive 
side.  The  way  to  determine  this  is  by  the  manner  in  which  the  films  are 
packed  in  the  envelopes.  Of  the  twelve  films  in  the  package,  eleven  have 
the  sensitive  surface  presenting  away  from  the  seam  of  the  enclosing 
envelope.  The  twelfth  film — the  one  farthest  from  the  seam — has  the 
sensitive  surface  presenting  inward  the  seam. 

Because  it  is  efficacious  and  is  furnished  promptly  and  at  a  reasonable 
cost,  the  most  popular  dental  X-ray  film  is  the  Eastman  film  supplied 
in  -mall  packets.  The  black  paper  of  the  packet  is  thick  enough  to  pro- 
tect the  film  against  moisture  when  taking  pictures  of  the  upper  teeth, 
but  additional  protection  is  needed  when  making  radiographs  of  the  lower 


M.IK  IXC  DENTAL  RADIOGRAPHS  87 

teeth.  This  protection  may  be  given  by  covering  the  packet  with  rubber 
clam.  The  rubber  dam  is  staked  out  with  pins  to  prevent  curling,  and 
covered  with  ordinary  rubber  cement,  such  as  is  used  to  repair  the  inner 
tubes  of  bicycles  and  automobile  tires.  Allow  the  cement  to  dry  a  minute 
or  so.  Place  the  packet  on  one  end  of  the  rubber,  remove  the  pins  at 
said  end,  and  fold  the  rubber ;  so  covering  the  packet.  Trim  off  the 
excess  rubber.     (Fig.  78.) 


Fig.   79.     Illustrating  method   of  covering  a  more  or   less   circular   film   with   black   paper. 

This  method  of  protecting  the  film  against  moisture  is  so  much  better 
— easier,  quicker,  more  efficient,  and  less  expensive — than  the  usual 
method  of  covering  the  film  with  unvulcanized  plate  rubber  that  a 
description  of  the  latter  will  not  be  given. 

Lately  I  have  adopted  a  method  of  covering  film  packets  to  protect 
them  against  moisture,  that  is  just  as  efficacious  and  much  more  con- 
venient and  less  expensive  than  the  one  just  described.  Take  a  piece  of 
mending  tissue,  such  as  is  used  by  tailors  to  mend  clothing,  of  such  size 
that  when  folded  over  the  film  packet  (Fig.  78,  C  and  D)  it  will  extend 
beyond  the  packet  on  the  three  open  slides,  about  one-half  inch.  Warm 
the  edges  of  the  tissue  slightly  by  passing  over  the  flame  of  an  alcohol 
lamp  or  Bunsen  burner,  and  pinch  them  together.  Then  warm  them  ( the 
edges)  to  stickiness  again  and  turn  them  back  and  stick  them  to  the  tissue 
covering  the  back — ;'.  c,  the  nonsensitive  side  of  the  film  packet. 

If  the  large  II ford  or  Eastman  films  are  used  the  operator  may  cut 
the  original  large  film  into  any  size  or  shape,  and  cover  with  two 
thicknesses  of  black,  lightproof  paper.  This  must,  of  course,  be  done  in 
a  dark  room.  A  pair  of  scissors,  with  long,  sharp  cutting  blades,  will 
be  found  especially  suitable  for  this  work.    Cover  the  film  so  the  sensitive 


88  DENTAL   RADIOGRAPHY 

will  be  the  smooth  side  of  the  packet.  Fig.  79  illustrates  a  method  of 
wrapping  up  more  or  less  circular  or  oval  films.  By  unwrapping  an 
Eastman  film  packet  one  can  learn  how  best  to  cover  a  square  or  rectangu- 
lar film.  If  the  films  are  to  be  used  to  radiograph  the  lower  jaw  or  teeth 
the  packet  should  be  cohered  with  rubber  dam  as  described.  Two  films 
may  be  put  in  a  packet  if  desired.  The  advantages  of  this  are  as  follows : 
If  one  negative  is  spoiled,  or  spotted  during  development,  possibly  the 
other  will  not  be.  If  the  patient  be  referred  from  another  dentist  or 
physician,  one  negative  may  be  given  to  the  man  referring  the  case  and 
the  other  retained  and  filed  away. 

Instead  of  wrapping  the  film  in  black  paper,  as  suggested  above,  one 
may  have  little  black  paper  envelopes  of  the  desired  size  made  and  use 
them.  Instead  of  using  rubber  dam,  one  may  have  small  oiled  paper 
envelopes  made  and  protect  the  films  against  moisture  by  enclosing  the 
packet  in  them. 

With  the  films  ready  for  use  we  may  now  proceed  as  follows : 

Be  it  understood  that  some  of  the  steps  in   the 

technic  for  technic*  given  hereinafter  are  for  the  beginner,  and 

Dental  may  be  eliminated  after  the  operator  is  acquainted 

Radiographs.  with  his  coil,  tubes,  films,  etc. 

First  test  the  coil  and  see  that  it  gives  a  fat, 
fuzzy  spark,  at  least  6  or  7  inches  long.  This  almost  invariably  neces- 
sitates cutting  out  all  the  resistance  of  the  rheostat.  I  cut  out  all  the 
resistance  of  the  rheostat  on  my  18-in.  induction  coil  and  obtain  a  fat, 
fuzzy  spark  10  inches  long. 

Some  of  the  most  modern  induction  coils  are  made  with  "multiple 
inductance."  With  this  equipment,  by  changing  a  plug  or  switch,  the 
induced  current  is  made  stronger  or  weaker  in  milliamperage.  The  higher 
the  milliamperage  sent  through  a  tube  the  greater  the  number  of  X-rays 
produced.  Thus  the  more  rapid  the  work  to  be  done  the  higher  the 
inductance  should  be.  Some  of  the  very  largest  induction  coils  on  their 
highest  inductance,  and  the  interrnpterless  coils,  can  force  30  or  40 
milliamperes  through  a  high  vacuum  X-ray  tube.  With  such  a  current 
dental  radiographs  can  be  made  instantaneously.  A  tube  will  not  stand 
such  a  current  without  injury  for  longer  than  about  fifteen  seconds  at 
most. 

Some  induction  coils,  nol  yet  on  the  market,  but  under  construction, 


*There  are   some   special   steps   in   technic   when   using  a  high-frequency  coil 
d  of  an  induction  coil  <>r  transformer.    These  stcp^  arc  not  mentioned  here, 
hut  will  be  found  immediatelj  following  tin-  summary  of  the  conditions  under  which 
the  negative  for  Fig,  L15  was  made. 


MAKING  DENTAL  RADIOGRAPHS 


89 


will  be,  if  we  are  to  believe  the  men  who  are  making  them,  able  to  force 
from  80  to  200  milliamperes  through  a  hard  tube.  A  tube  could  not 
stand  such  a  current  longer  than  a  second  or  so,  if  so  long. 

After  testing  the  coil,  throw  off  the  switch  and  hitch  up  the  tube. 
Have  the  terminal  tapes  tight,  so  they  will  not  come  unhooked  from 
the  tube  while  it  is  in  operation.  When  a  terminal  becomes  disconnected 
from  the  tube  while  the  current  is  passing  through  it  a  puncture  of  the 
tube  sometimes  results. 


Fig.    80.      Position    of  the   film    in   the   mouth    for   making   radiographs    of   the    upper    bicuspid    and 

first    molar    region. 


Set  the  tube-regulating  arm  to  give  a  tube-regulating  spark  gap  of  4 
inches.  This  is  not  an  invariable  rule.  Perhaps  the  gap  should  be  5 
inches  when  a  tube  is  new  and  reduced  to  3  or  2  inches  when  the  tube 
is  old.  And  so  with  many  statements  following — they  are  subject  to 
variation ;  they  are  calculated  only  to  give  a  beginner  something  tangible 
to  start  with. 

When  the  tube  is  hitched  to  the  coil,  separate  the  sliding  rods  the 
entire  distance  of  the  maximum  spark  gap.  See  to  it  that  the  terminal 
tapes  or  the  tube  are  not  near  any  conductor,  or  the  current  may  jump 
to  it — the  conductor.  If  this  occurred  from  the  tube  it  might  be 
punctured. 

Turn  on  the  switch  just  for  a  moment,  then  off,  then  on,  then 
off,  and  so  on,  slightly  lengthening  the  time  the  current  is  left  on  until 
it  is  observed  to  pass  through  the  tube  without  a  spark  at  the  tube-regu- 


DENTAL   RADIOGRAPHY 

lating  spark  gap.  This  warms  the  tube  gradually.  In  cold  weather  it 
is  well  to  warm  it  slightly  over  a  register  before  sending  the  current 
through  it.  Sometimes  no  spark  will  occur  at  the  tube-regulating  spark 
gap  at  all.  This  simply  means  that  the  vacuum  of  the  tube  is  such  that 
it  does  not  need  lowering.* 

Turn  the  current  on  now  for  a  few  moments  and  see  that  the  tube 
lights  up  properly.  In  order  to  observe  the  fluorescence  the  room  should 
be  either  dark  or  semi-dark.  Turn  off  the  current,  shorten  the  spark  gap, 
turn  on  the  current  again,  and  observe  whether  it  passes  through  the 
tube  or  jumps  the  spark  gap.  Repeat  this  until  the  current  jumps  the 
gap.  This  tells  us  the  condition  of  the  tube  by  showing  how  many  inches 
of  parallel  spark  it  will  back  up.  The  tube  should  back  up  about  6  inches 
of  spark.  After  the  operator  is  well  acquainted  with  his  tube  and  coil 
this  test  of  the  vacuum  of  the  tube  will  not  be  necessary.  The  operator 
will  be  able  to  judge  the  vacuum  fairly  well  by  the  fluorescence  of  the 
tube  and  the  length  of  the  tube-regulating  spark  gap. 

We  are  now  ready  to  pose  the  patient.  As  we  do  this  we  must 
constantly  bear  in  mind  that  we  are  simply  throwing  a  shadow  on  the 
film,  and  that,  like  all  shadows,  this  one  is  liable  to  be  distorted  unless 
the  tube,  the  part  to  be  radiographed,  and  the  film  are  in  their  proper 
relative  positions. 

The  ideal  position  would  be  so  that  the  X-rays  would  strike  the  part 
to  be  radiographed  and  the  film  at  right  angles,  as  in  Fig.  70.  But  this 
is  quite  impossible  when  radiographing  the  upper  teeth. 

With  the  film  in  the  mouth,  as  per  Fig.  80,  the 
Position  of  Tilm        common  mistake  will  be  to  have  the  tube  too  low 
and   Direction  (Fig.  81  ).     The  result  of  this  is  shown  in  the  radio- 

Of  Ray$.  graph  in  Fig.  81,  and  the  reason  for  it  in  the  dia- 

gram  (Fig.  82)   in  which  the  angle  of  the  rays,  the 
object,  and  the  film  are  in  about  the  same  relative  positions  as  in  Fig.  81. 
The  proper  position  and  the  radiograph  made  from  this  pose  are 
shown  in  Fig.  83.    Fig.  84  diagrammatically  illustrates  the  pose  in  Fig.  83. 


'Instead  of  setting  the  tube  regulating  spark  gap  at  a  certain  distance  and  leav- 
ing it  there  while  the  exposure  is  being  made,  as  T  have  suggested  and  will  continue 

j-cst,  it  i-  th<-  common  practice  for  radiographers  to  make  the  tuhe-regulating 
-park  gap  short — i.  c.  about  two  or  three  inches — turn  on  the  current  for  a  second 
or  a  fraction  thereof,  until  the  tube  lights  up  properly,  then  widen  the  gap  to  its 
maximum  length,  then  turn  on  the  current  again  foi  a  moment  to  see  that  the  tube 
lights  np  properly  with  the  gap  so  widened,  and,  if  so,  make  the  exposure  with  the 
Hap  it>  maximum  width,  a  distance  too  greal  for  sparking  to  occur.  If,  after  low-  r- 
ing  the  vacuum,  inverse  current  is  seen  in  the  tube  it  means  thai  the  vacuum  has 
been  lowered  too  much,     \llow  the  tube  to  cool 


MAKING  DENTAL  RADIOGRAPHS 


9i 


Fig.   81.      The   tube  too  low,   and  the  resulting  radiograph. 


Fig.    S5.      Diagrammatic   illustration   of   the   X-rays   striking   the   tooth    and   film    at   such    an    angle 

as    to    cause   a    lengthening    of    the    shadow    cast    on    the    film.       (For    this    idea    of    diagrammatic 

illustration    the    writer   is   indebted    to    Dr.    Price.) 


DENTAL   RADIOGRAPHY 


Fig.   83.     The  proper  pose   for  making  radiographs  of  the   upper  bicuspid   and   molar    region,   and 
the   radiograph   which   was  made   from   this  pose. 


34.     Diagrammatic  illustration  "f  the   raya  striking  the  tooth  and  film  at  such  an  angle  as 
i»    avoid    cither    lengthening    or    shortening    the    shadow    cast    on    the    film. 


MAKING  DENTAL  RADIOGRAPHS 


93 


^k    C 

■  i      rV> 

Fig.    85.      The   tube   too   high,   and   the   resulting   radiograph. 


Film 


Fig.   86.      Diagrammatic   illustration   of   the    rays   striking   the   tooth   and   film   at   such   an   angle   as 
to    cause    a    shortening    of   the    shadow    cast    on    the    film. 


• 


DENTAL  RADIOGRAPHY 


If  the  tube  be  placed  too  high  the  teeth  on  the  radiograph  will  be 
shorter  than  the  teeth  themselves,  somewhat  distorted  and  blurred  (Fig. 
Fig.  86  diagrammatically  illustrates  the  pose  in  Fig.  85. 

A  study  of  Figs.  82,  84  and  86  will  show  that  in  order  to  make 
a  radiograph  which  will  not  picture  the  teeth  too  long  nor  too  short  the 
X-rays  should  strike  the  film  almost,  but  not  quite,  at  right  angles  to  its 
surface.     The  angle  of  the  film  in  Figs.  82,  84  and  86  is  what  it  would 


Film 


Fig.    87. 


be  in  the  average  mouth.  Suppose,  however,  the  vault  is  very  flat.  In 
such  an  event  the  angle  of  the  X-rays  as  illustrated  in  Fig.  84  to  be  cor- 
rect would  cause  a  marked  lengthening  of  the  shadow,  as  illustrated  by 
the  dotted  lines  and  drawing  in  Fig.  87.  The  angle  of  the  X-rays  should 
be  as  in  Fig.  86  to  avoid,  as  nearly  as  possible,  any  distortion.  (Notice 
in  Fig-  87  that  the  bending  of  the  film  would  cause  a  lengthening  of  the 
shadow.) 

Just  in  proportion  as  the  vault  becomes  more  flat  the  film  departs 
from  the  vertical  and  the  tube  must  be  at  a  different  and  higher  angle. 
And  so,  inversely,  as  the  vault  is  higher  the  film  may  be  placed  more 
nearly  parallel  with  the  teeth  and  the  tube  may  be  lowered. 

From  the  foregoing  it  will  be  understood  why  we  can  never  be  sure 
that  our  radiograph  gives  the  exact  length  of  Upper  teeth. 


MAKING  DENTAL  RADIOGRAPHS 


95 


Owing  to  the  fact  that  it  causes  distortion,  bending  of  the  film  should 
be  avoided  as  much  as  possible. 

Fig.  83  shows  the  proper  pose  for  making  a  radiograph  of  the  bicus- 
pid region.  The  slight  changes  of  this  pose  necessary  to  make  radio- 
graphs of  the  anterior  and  extreme  posterior  teeth  are  apparent.  When 
making  radiographs  of  the  posterior  upper  teeth  the  mistake  at  first  will 
probably  be  that  the  X-rays  will  not  be  directed  at  a  point  far  enough 
back  on  the  face  and  pictures  of  the  bicuspids  will  be  made  when  the 
operator  desired  to  picture  the  molars. 


Fig.   88.     As   a   film   is  placed   in   the    mouth    for   the   pose   and   radiograph    shown   in    Fig.    89. 


Instead  of  placing  the  film  in  the  mouth,  as  in  Fig.  80,  a  larger  film 
may  be  used  and  placed  as  in  Fig.  88,  the  sensitive  side  toward  the 
upper  teeth.  With  the  film  in  this  position  the  patient  is  instructed  to 
close  the  mouth,  so  holding  the  film  firmly  in  position.  With  the  film 
in  such  a  position  either  the  tube  must  be  placed  higher  and  the  rays 
directed  more  nearly  straight  down ;  or  the  head  must  be  tipped  down- 
ward toward  the  tube,  which  accomplishes  the  same  result,  viz.,  causes 
the  rays  to  strike  the  film  more  nearly  at  right  angles.  (Fig.  89.)  The 
radiograph  made  on  a  film  held  in  this  position  is  very  likely  to  be  dis- 
torted.  (Fig.  89.) 

The  usual  position  of  the  film  for  taking  pictures  of  the  lower 
teeth  is  illustrated  in  Fig.  90.  With  the  film  in  this  position  it  should 
be  covered  with  rubber  or  oil  paper  to  protect  it  against  moisture. 

Fig.  91  shows  the  proper  pose  for  taking  pictures  of  the  lower  bicus- 
pid and  molar  region.     If  the  radiograph  does  not  show  the  apices  of 


DEXTAL  RADIOGRAPHY 


Pig,    -■'.     The  pose  with  the  film  in  the   mouth,   a-  in   Fig.   88,  ami  the  radiograph   made 

from   this   pose. 


the  roots  it  is  because  the  film  was  not  pressed  down  far  enough,  or  the 
tube  was  not  low  enough.  The  slight  differences  in  the  poses  to  make 
radiographs  of  the  anterior  teeth  and  the  third  molars  from  the  pose 
shown  in  Fig.  91  are  apparent. 

With  the  film  placed  in  the  mouth  as  in  Fig.  89.  except  with  the 
sensitive  side  of  the  film  presenting  toward  the  lower  instead  of  the  upper 
teeth,  and  a  pose  as  per  Fig.  92,  radiographs  of  the  lower  teeth  may  be 
made. 


MAKING  DENTAL  RADIOGRAPHS  97 

The  distance  the  tube   is  placed   from   the  film 

Distance  Between        is  about  12  to  20  inches,  measurements  taken  from 

Cube  and  Patient.       the  target  of  the  tube.     A  good  rule  to  follow  is  to 

place  the  tube  so  that  there  is  a  distance  of  about  8 

inches  between  the  glass  of  the  tube  and  the  patient's  face.    If.  as  is  almost 

invariably  the  case,  a  6-inch  tube  is  used,  this  makes  the  distance  between 

the  target  and  him  about  12  to  13  inches.*     1  never  have  the  glass  of  the 


Fig.    90.      Position    of    the    film    in    the    mouth    for    making    radiographs    of    the    lower    molar    and 

bicuspid   region. 


tube  closer  than  6  inches  from  the  face.  A  tube  of  medium  vacuum  must 
be  brought  a  little  nearer  to  the  film  than  one  of  high  vacuum  if  the  same 
length  of  exposure  is  to  be  made,  because  the  X-rays  from  it  are  not 
so  penetrating.  The  advantage  in  having  the  tube  as  far  away  as  possi- 
ble lies  in  the  fact  that  both  the  patient  and  film  are  then  more  nearly 
out  of  range  of  the  soft,  secondary  rays.  These  rays  may  burn  the  pa- 
tient (set  up  a  dermatitis)   and  fog  the  film. 

In  most  works  on  radiography  the  writers  advise   18  inches  as  the 
proper  distance  between  target  and  film.     I  believe  this  to  be  needlessly 


*Eight  inches  between  the  glass  of  the  tube  and  the  patient's  face,  plus  three 
inches  the  distance  from  the  glass  of  the  tube  to  the  target,  plus  one  to  two  inches 
the  thickness  of  the  maxilla  and  overlying  parts,  equals  twelve  to  thirteen  inches 
the  distance  between  the  target  and  the  film. 


DENTAL    RADIOGRAPHY 

long.  As  1  have  just  stated.  1  bring  my  tube  much  closer,  and  I  have 
never  had  any  trouble  from  dermatitis  or  fogging  of  the  radiograph.  By 
bringing  the  tube  as  close  as  I  do  1  am  able  to  get  a  clearer,  better  pic- 
ture in  about  one-half  the  time  of  exposure  that  would  be  required  if 
the  distance  between   the  target  and   the   film   were   l8   inches. 

Before  placing  the  film  in  the  mouth,  after  the  tube  and  the  patient 
are  in  their  proper  positions  it  is  well  to  turn  on  the  current  for  a  mo- 
ment, that  the  patient  may  become  accustomed  to  the  sound  and  light. 
Otherwise  the  patient  would  probably  be  startled,  move  involuntarily  and 
spoil  the  picture. 

1  f  the  films  have  been  in  the  same  room  while 

Protection  we  have  been  testing  the  tube,  or  even  if  they  have 

Of   Tilm$.  been  in  a  room  immediately  adjoining  the  operating 

room,  they  must  have  been  kept  in  an  X-ray  proof, 

lead-lined  box.  the  lead  of  which  should  be  about  %  inch  thick  (  Fig.  93). 

All  films,  plates  or  papers  must  be  kept  in  such  a  box  if  they  are  to  remain 

in  the  same  room,  or  even  an  adjoining  room,  while  the  tube  is  lit,  to 

keep  them  from  becoming  fogged. 

If  the   position   of   the   film   is  as   per   Fig.   88, 

methods  of  whh  the  mouth  closed,  the  problem  of  holding  the 

fiolding  Tilms  film   while  making  the  exposure  is   solved.     If,   as 

in  the  lllouth.  in  Figs.  80  or  90,  however,  the  film  must  be  held 

immovable  by  either  patient,  assistant,  or  operator. 
The  patient  can  hold  the  film,  and  it  is  best  that  he  should.  If  the  oper- 
ator or  assistant  holds  it  he  or  she  should  wear  X-ray  proof  gloves  to 
protect  the  hands.  Otherwise  the  repeated  exposure  of  the  hands  to  the 
rays  might  prove  disastrous.     See  chapter  on  "Dangers  of  the  X-Rays." 

Dr.  Tousey,  of  New  York,  and  Dr.  Ketcham,  of  Denver,  have  de- 
signed little  devices,  film  holders,  for  holding  the  film  in  the  mouth  during 
it-  exposure. 

It  has  been  recommended  that  a  modeling  composition  impression 
of  the  mouth  may  be  made,  a  place  cut  out  for  the  film,  which  is  placed 
therein  and  the  impression  reinserted  in  the  mouth.  This  method  of 
holding  films  I  consider  extremely  impracticable,  because  of  the  time 
consumed  in  unnecessary  work  and  the  considerable  bending  of  the  film. 

When  using  square  or  rectangular  film  packets  bend  the  sharp  cor- 
ners to  keep  them  from  digging  into  the  tissues  of  the  month. 

When  making  radiographs  of  the  lower  teeth  with  the  film  in  the 
month,  as  per  Fig.  90,  the  patient  should  be  warned  not  to  swallow  during 
the  exposure.  Movemenl  of  the  tongue  in  swallowing  would  move  the 
film. 


MAKING  DliXTAL  RADIOGRAPHS 


99 


Fig.    91.      Proper    pose    for    making    radiographs    of    the    lower    molar    and    bicuspid    region,    and 
the   radiograph   made    from   this   pose. 


As  stated  in  Chapter  IV,  the  length  of  time  of 
time  Of  exposure  depends  on  several  things.     With  the  coil 

Exposure.  capable  of  giving  a  fat,  fuzzy  spark  10  inches  long, 

the  tube  backing  up  7  inches  of  parallel  spark  and 
the  distance  of  the  target  from  the  film  about  12  inches,  the  time  of  ex- 
posure for  an  Eastman  film  will  be  between  5  and  10  seconds. 

I  have  seen  tables  giving  the  exact  time  of  exposure  for  the  differ- 
ent teeth — upper  molar  teeth  so  many  seconds,  upper  anterior  teeth  so 
manv  seconds,  lower  molar  teeth  so  many  seconds,  and  so  on — but  such 
tables  are  utterly  useless.  No  fixed  rules  for  the  length  of  time  of 
exposure  can  be  made  and  adhered  to.  For  example,  I  had  been  making 
10-second  exposures.     I  purchased  a  new  tube — the  same  make  tube  I 


IOO 


/ CENTAL  RADIOGRAPHY 


Fig.  92.  Pose  for  making  radiographs  of  the  lower  anterior  teeth,  and  the  radiograph  made 
from  this  pose.  The  lack  of  detail  in  this  radiograph  is  due  to  the  fact  that  a  negative 
cinematograph  film  was  used.  When  a  terminal  of  the  tuhe  is  brought  as  close  to  the  patient 
as  is  shown  in  this  picture  it  is  necessary  to  place  a  piece  of  wood  or  glass,  or  some  other 
non-conductor,  between  the  terminal  and  the  patient — in  this  case  over  the  patient's  breast — to 
prevent  the  current  "sparking"  into  the   patient. 


had  been  using — and  found  that  with  it  pictures  could  be  made  in  half 
the  time,  g  seconds.  Then  after  using  the  tube  a  few  weeks  it  became 
necessary  to  again  increase  my  time  of  exposure  to  10  seconds. 

As  to  a  longer  exposure  being  required  for  some  teeth  than  for 
others,  very  little  need  be  said.  The  time  of  exposure  for  radiograph- 
ing third  molars  is  slightly  longer  than  for  any  other  teeth  oi  the  same 
mouth. 

Age  increases  the  density  of  hone,  and  so  the  time  of  exposure  neces- 


MAKING  DENTAL  RADIOGRAPHS  101 

sary  to  make  radiographs  will  be  somewhat  proportionate  to  the  age  of 
the  patient. 

The  time  of  exposure  can  be  shortened   from 

(ISC  of  one-half    to    four-fifths    by    using    an    intensifying 

Intensifying  Screen.      screen.     An  intensifying  screen  is  a  piece  of  paper, 

or    cardboard    covered    with    calcium    tungstate,    or 

platino-barium  cyanide. 

The  coated  side  of  an  intensifying  screen  is  placed  against  the  coated 


Fig.    93.      Lead-lined,   X-ray-proof   box. 

side  of  the  film  or  plate,  and  both  screen  and  film  are  placed  in  the  light- 
proof  packet  as  usual.  Thus  we  get  a  double  action  on  the  film  when 
it  is  exposed,  the  action  of  the  X-rays  themselves  and  the  action  due  to 
the  fluorescence  of  the  intensifying  screen. 

When  using  an  intensifying  screen  the  uncoated  side  of  the  film 
should  present  toward  the  object  being  radiographed.  This  is  contrary 
to  the  rule  that  to  obtain  the  best  results  the  coated  side  of  the  plate  or 
film  should  present  toward  the  object  to  be  radiographed. 

The  advantages  of  the  intensifying  screen  are:  (i)  Just  in  propor- 
tion as  it  reduces  the  time  of  exposure  it  protects  both  patient  and  oper- 
ator against  any  ill-effects  of  the  X-rays.  (2)  By  shortening  the  time  of 
exposure  the  life  of  the  tube  is  lengthened.     From  a  financial  standpoint 


[02  DENTAL   RADIOGRAPHY 

this  is  of  importance.     (3)   By  using  an  intensifying  screen  one  is  able 
to  do  tolerably  rapid  work  even  with  a  very  small  coil. 

The  disadvantages  of  the  intensifying  screen  are:  (1)  It  causes  a 
granular  appearance  of  the  negative,  blotting  out  detail.  (2)  It  is  liable 
to  spot  the  negative,  due  to  unequal  fluorescence  of  its  surface.  (3)  It 
fluoresces  for  a  minute  or  so  after  exposure,  and  if  the  plate  and  screen 
do  not  maintain  their  exact  relation  to  one  another  blurring  of  the  nega: 
tive  results.  (4)  Unless  one  owns  several  screens,  so  that  a  number  of 
packets  may  be  made  at  a  time,  their  use  necessitates  the  making  of  a 
film  packet  before  each  exposure,  which  is  discommoding. 

Such  grosser  lesions  as  an  impacted  tooth,  for  example,  can  be  radio- 
graphed satisfactorily  with  the  intensifying  screen,  but  when  we  wish  to 
obtain  detail,  such  as  is  necessary  to  observe  pulp  stones  or  a  necrotic 
condition,  for  example,  the  use  of  the  intensifying"  screen  is  contraindi- 
cated.     An  intensifying  screen  disintegrates  with  use. 

Because,  as  I  have  said,  the  intensifying  screen  fluoresces  for  some 
time  after  the  the  exposure  has  been  made  it  has  been  the  practice  of 
radiographers  to  lay  the  plate  and  screen  aside  for  some  time  before  dis- 
turbing their  relation  to  one  another.  Dr.  Sidney  Lange,  however,  be- 
lieving that  the  continued  fluorescence  will  cause  blurring  .of  the  negative 
even  though  the  relation  of  the  screen  to  the  plate  be  not  disturbed. 
removes  the  plate  from  the  screen  immediately  after  exposure.  His  re- 
sults from  this  practice  are  excellent. 

After  the  film  has  been  exposed  we  are  ready  to 

Development  develop  it — to  make  the  negative. 

Of  negative.  The   trays   for   the   developer  and    fixer   should 

be  about  4x5  inches,  or  smaller.    The  author  uses  little  white  enamel  soap 
dishes,  about  3x4  inches. 

If.  owing  to  the  particular  developer  or  film  used,  development  re- 
quires a  ci  'ii>iderable  length  of  time,  say,  perhaps  20  minutes,  and  one  does 
not  wish  to  remain  all  this  time  in  the  dark  room,  the  tray  containing  the 
developer  and  developing  negative  may  be  covered  with  a  heavy  board 
on  the  down  side  of  which  is  tacked  or  glued  thick  felt  or  plush,  and  the 
operator  may  then  leave  and  return  to  the  dark  room  at  will,  the  film 
hem-  protected  against  the  lighl  from  the  opening  of  the  dark  room 
door. 

Whal  developer  shall   we  use?     I   obtained  the 

Choice  of  formula^  for  the  developers  used  by  twelve  different 

Developer.  radiographers,  and   they   were  all  different!     From 

this  we  may  conclude  that  any  clean,  properly  mixed 

developer  will  do  the  work. 

The   writer  uses   a   prepared   developer    which    may  be   purchased    at 


MAKING  DENTAL  RADIOGRAPHS  103 

almost  any  photographic  supply  store,  the  Eastman  M.  O.  developer,  the 
formula  for  which  is  given  in  Chapter  IV.  This  developer  is  sold  for 
developing  photographic  paper,  but  it  develops  films  and  plates  perfectly. 
The  lahel  on  the  tube  containing  the  chemicals  directs  that  they  be  mixed 
with  4  ozs.  of  water  for  one  kind  of  photographic  paper,  '"Regular  Ve- 
1<>\."  and  8  ozs.  for  two  others,  "Azo"  and  "Special  Yelox."  1  use  6  ozs. 
of  water.  After  the  powder  is  dissolved  in  the  water  in  my  graduate  I 
put  3  ozs.  of  the  solution  in  the  tray  for  immediate  use  and  3  ozs.  in  a 
3-oz.  amber  glass  bottle.  In  this  bottle,  tightly  corked,  the  developer 
will  keep  as  long  as  a  month.     Even  if  it  does  discolor  slightly  it  can 


Fig.    94.      Films   hung   up   to   dry 

still  be  used  for  negatives,  though  it  might  stain  paper.  When  the  nega- 
tives are  developed — one  or  many  may  be  developed — the  developer  in 
the  tray  is  thrown  away.  I  never  try  to  save  developer  that  has  been 
used,  with  the  idea  of  using  it  again  in  the  future. 

Since  writing  the  foregoing  I  have  been  using  another  prepared  de- 
veloper, rodinal.  My  limited  experience  with  it  teaches  me  to  believe  that 
it  is  as  good  as  the  M.  O.  developer.  My  chief  reason  for  using  it,  how- 
ever, is  because  it  is  so  extremely  convenient  to  handle.  It  is  a  liquid. 
When  I  wish  to  develop  a  film  I  take  2^/2  ozs.  of  tap  water  to  2  drams 
of  rodinal.  This  makes  a  1-10  solution.  The  water  and  the  rodinal 
are  simply  placed  in  the  tray  together,  and  the  developer  is  ready  for 
use ;  one  does  not  need  to  wait  for  powders  to  dissolve. 

When  conditions  and  length  of  exposure  are  as  given  above,  the  time 
the  film  remains  in  the  developer  is  usually  about  5  minutes ;  the  high 
lights  come  up  in  about  15  seconds  and  the  image  can  be  seen  tolerably 
well  in  30  seconds. 


104  DEXTAL  RADIOGRAPHY 

The  time   in   the   fixer  varies   according  to   the 

fixing  and  film  used.     The  Eastman  film  requires  about  5  min- 

Wasbing.  utes;  the  Ilford  film,  because  it  is  so  much  thicker, 

15  or  20  minutes. 

The  writer  uses  a  prepared  acid  fixing  powder,  mixing  about  a 
pint  at  a  time.  The  solution  will  keep  indefinitely.  As  with  the  de- 
veloper, no  attempt  is  ever  made  to  save  for  future  use  any  of  the  solu- 
tion once  used. 

The  negative  should  be  washed  in  running  water  for  15  to  30  min- 
utes, then  hung  up  to  dry.     (Fig.  94.) 

Instead  of  washing  the  negative  in  water  for  15  to  30  minutes  it 
may  be  soaked  in  Thioxydant,  a  '"hypo  eliminator,"  for  about  five  min- 
utes. This  dissolves  out  all  the  "hypo,"  and  so  accomplishes  the  object 
of  washing.  Thioxydant  is  a  proprietary  preparation  made  by  the  Lu- 
miere  Dry  Plate  Mfg.  Co.  The  advantage  in  using  it  lies  chiefly  in  the 
saving  of  time.  It  may  also  be  used  in  the  summer  to  advantage,  when 
tap  water  is  so  warm  that  it  softens  the  emulsion  and  washing  is  fraught 
with  the  liability  of  spoiling  the  negative.  It  may  be  used  for  photo- 
graphic paper  as  well  as  for  plates  and  films. 

Drying  requires  several  hours,  unless  the  negatives  are  placed  in 
the  breeze  of  an  electric  fan  as  suggested  in  Chapter  IV.  It  requires  a 
longer  time  for  the  Ilford  negative  to  dry  than  for  the  Eastman  product, 
because  the  emulsion  on  it  is  thicker. 

When  the  negative  is  dry  we  may  then  make 

making  as  many  prints   therefrom  as  desired,   immediately 

Prints.  or  years  after.     The  technic  for  making  prints  was 

given  in  the  preceding  chapter. 

The  negative  is  laid  on  the  glass  in  the  printing  frame,  film  side  up, 

and  the  paper  placed  over  it  sensitive  side  down,  and  so  on  as  given. 

The  best  prints  can  be  made  on  glossy,  contrasted  paper.     Using  glossy, 

contrast}-  Azo  paper,  the  time  of  exposure  to  a  16-candle  power  electric 

light  at  a  distance  of  about  a  foot  is  from  1  to  10  minutes.     When  the 

negative  is  badly  overexposed  or  overdeveloped,  and  it  is  therefore  verv 

dark,  the  time  of  exposure  to  a  16-candle  power  electric  light  may  be  as 

long  as  20  to  30  minutes.    If  the  exposure  be  made  to  sunlight  instead  of 

the  electric  light  tlii-  time  may  be  reduced  to  a  couple  of  seconds.     I  use 

M.  Q.  developer  to  make  my  prints. 

Lately  1  have  used,  with  a  moderate  degree  of  satisfaction,  a  sunlight 
photographic  paper  made  by  the  Eastman  Kodak  Company  and  sold  under 
the  trade  names  of  "Solio"  ami  "Kresko."  Unlike  the  photographic 
papers  thus  far  described,  this  paper  is  not  affected,  except  alter  pro- 


MAKING  DENTAL  RADIOGRAPHS  105 

longed  exposure,  by  ordinary  daylight.     So  the  room  in  which  it  is  used 
need  be  neither  dark  nor  semi-dark. 

The  exposure  must  be  made  to  sunlight,  and,  for  the  average  cellu- 
loid, dental  negative  is  about  one  hour  long.  At  the  end  of  this  time  the 
picture  is  printed.  It  can  be  seen,  and  needs  no  developing  to  bring  it  out 
as  other  photographic  papers  do.  At  this  stage  the  picture  looks  like  and 
in  fact  is  a  "proof,"  the  like  of  which  photographers  submit  to  their 
patrons.  It  will  "fade"'  or,  to  speak  more  accurately,  become  dark  and 
so  blot  out  the  picture,  as  all  proofs  do,  unless  the  unacted-upon  silver 
salt  is  dissolved  out.    This  may  be  accomplished  and  the  print  made  per- 


Fig.    95.     A    roller. 

manent  by  placing  it  in  an  ordinary  fixing  solution  for  about  eight  min- 
utes. Then  it  is  transferred  to  running  water"  and  washed  for  about  an 
hour. 

Instead  of  using  the  ordinary  fixing  bath  much  better  results  may  be 
obtained  by  placing  the  print  in  "Solio  Toning  Solution,"  a  preparation 
made  by  the  Eastman  Kodak  Company.  This  solution  not  only  fixes  the 
print  by  dissolving  the  unacted-upon  silver  salt,  but,  because  it  contains 
gold  chloride,  changes  the  color  from  a  reddish-brown  to  a  rich  choco- 
late, and  so  makes  a  better-looking  print. 

A  printing  frame  the  back  of  which  is  in  two  pieces  joined  with  a 
hinge  (Fig.  jj)  is  necessary  for  this  work.  By  releasing  only  part  of  the 
back  and  raising  it  on  its  hinges,  we  may  look  at  the  print  from  time 
to  time  in  the  course  of  its  development,  without  altering  the  relative 
positions  of  the  negative  and  paper. 

The  greatest  disadvantage  in  using  this  paper  lies  in  the  fact  that  we 
must  have  sunlight  for  our  exposures.  In  this  climate  (Indiana)  many 
days  pass  without  any  sunshine  and,  during  such  a  period,  sunlight  paper 
cannot  be  used  successfully. 

The  directions  given  for  the  use  of  "Solio  Toning  Solution'*  advise 


io6 


DENTAL   RA1UOCKAPHY 


placing  the  print  in  a  solution  of  sodium  chloride,  for  five  minutes,  after 
mova]  from  the  toning  solution,  before  placing  it  in  the  wash  water. 
This  step  is  not  imperative. 

Prints  may  be  made  more  glossy  and  altogether  more  beautiful  by 
placing  them  on  a  ferrotype,  or  squeegee  board.  The  ferrotype  is  a  sheet 
of  metal  on  one  side  of  which  is  baked  black  enamel.  After  the  prints 
are  washed  they  are  laid  face  down  on  the  enamel  side  of  the  ferrotype, 
rolled  with  a  roller  (Fig.  95),  covered  with  a  lintless  blotter  and  rolled 


Fig.   9';.      Film    packet    held   against    the    cheek    with    adhesive    tape. 


again  with  a  roller.  The  ferrotype  is  now  set  on  end,  and  as  the  prints 
dry  they  fall  off.  Before  placing  the  prints  on  the  ferrotype  the  enamel 
surface  should  be  polished  with  ferrotype  polish.  Ferrotype  polish  is  a 
solution  of  paraffin  in  benzine.  It  is  put  on  the  ferrotype,  allowed  to  dry 
for  a  few  minutes,  then  the  enamel  surface  polished  with  chamois  skin. 
If  the  prints  do  not  come  off  the  ferrotype  as  they  should,  but  stick 
tightly,  mor,-  paraffin  should  be  added  to  the  polishing  solution.  The  most 
common  cause  for  prints  sticking  to  the  squeegee  board,  however,  is  the 
failure  to  allow  them  to  dry  thoroughly. 

In  all  the  poses  thus  far  described  the  film  has 

Placina  films  been  placed  inside  the  mouth.    Though  it  is  not  of  ten 

Outside  the  expedient  to  do  so,  because  of  the  longer  exposure 

Ittoutb.  necessarv,  it   i-   nevertheless   sometimes  advisable  to 

place  the   film  outside  the  mouth.   (Fig.  96.)     The 


MAKING  DENTAL  RADIOGRAPHS 


107 


film  packet  may  be  held,  sensitive  side  toward  the  cheek,  with  adhesive 
tape.  With  the  film  placed  as  in  Fig.  96,  the  pose  should  be  as  in 
Fig.  97.     The  time  of  exposure  for  this  pose  is  about  six  times  as  long 


Fig.    07.      Pose  for  making   a   radiograph   of   the   lower   molar   region   with   the   film   outside   of  the 
mouth,    as    in    Fig.    !*fi.    and    the    radiograph    made    from    this    pose. 


as  it  would  be  if  the  film  were  placed  inside  of  the  mouth  and  the  same 
field  radiographed.  The  increase  in  time  exposure  necessary  is  due  to 
three  things :  First,  the  increased  distance  between  the  target  and  the 
film.  Second,  the  great  thickness  of  tissue  to  be  penetrated.  Third,  the 
increased  distance  between  the  teeth  and  the  film;  the  closer  the  object  to 
be  radiographed  is  to  the  film  or  plate  the  better  and  more  quickly  it  can 
be  radiographed. 


ro8 


DENTAL   RADIOGRAPHY 


Owing  to  the  curvature  of  the  dental  arch  it  is  often  extremely  diffi- 
cult to  obtain  a  good  picture  of  the  lower  incisors  with  the  film  placed 
to  the  lingual  and  parallel  to  the  long  axis  of  the  teeth.     This  is  because 


FiK.    !)-.      Pose    for    making   a    radiograph    of   the    lower   incisors,    and    the   antra. 


the  film  cannot  be  placed  in  this  position  without  bending  it  considerably, 
and  the  bending  results  in  distortion  and  blurring  of  the  radiograph.  A 
film  may  be  placed  in  the  mouth  as  in  Fig.  92,  or  a  plate  or  large  film, 
4x5  inches  or  larger,  may  be  placed  on  a  stand,  sensitive  side  up,  and  the 
patient  posed  as  in  Fig.  98.  It  is  usually  necessary  to  have  the  patient 
remove  the  collar  for  this  pose.  Fig.  98,  because  of  its  lack  of  per- 
spective, is  perhaps  a  little  misleading.  The  rays  are  not  directed 
straighl  through  the  neck,  as  the  picture  seems  to  show.     The  tube  is  a 


MAKING  DENTAL  RADIOGRAPHS 


109 


Fig.  99.     Radiograph  made  from  the   pose  shown  in   Fig.   9S.     Notice  how   clearly  the   antra  show 


little  to  one  side.  Fig.  99  is  the  radiograph  made  from  the  pose  Fig.  98. 
Notice  how  clearly  the  antra  of  Highmore  show  in  this  picture.  I  be- 
lieve that  in  posing  my  patient  as  just  described  to  make  radiographs  of 
the  lower  incisors  I  have  by  accident  stumbled  on  to  the  best  pose  for 
making  pictures  of  the  antra. 

Except  Fig.  98,  all  of  the  poses  so  far  described  have  been  with  the 
patient  in  the  dental  chair,  and  films  have  been  used. 


no 


DENTAL   RADIOGRAPHY 


Poses  for 
targe  Plate 
Radiographs. 


To  make  the  radiograph  shown  in  Fig.  ioo  the 
pose  was  as  in  Fig.  101  and  the  radiograph  was 
made  on  a  5x7  plate. 

Fig.  101  illustrates  the  principle  of  posing  for 
large  plate  radiographs.     Modifications  of  this  pose 


pig,     Radiograph    made    from    the    pose    similar    to    Fig.    101,      The    arrow    points    to    an 

impacted    upper    third    molar.      Th<     lack    of    detail    in    this,    and    all    radiographs    made    from    a 

similar   pose,    i-   due    to   a    superimposition    of   shadows     the   shadow   of    one    side   of   (lie   jaw   is 

mingled  with  the  shadow  of  the  other.     (Radiograph  by  A.   M.  Cole  and  Raper.) 


are  of  course  necessary,  according  to  whal   particular  region   is  to  be 
pictured. 

The  objection  to  this  pose  as  illustrated  is  that  the  part  being  radio- 


MAKING  DENTAL  RADIOGRAPHS 


1 1 1 


graphed  is  not  close  enough  to  the  plate.  With  the  apparatus  used  the 
patient  could  not  be  posed  lying  on  the  side,  because  the  shoulder  would 
have  been  in  such  a  position  that  the  tube  could  not  have  been  brought 
close  enough  to  the  part.  The  pose  would  have  been  better  had  the  patient 
been  lying  on  the  stomach  with  the  head  turned  to  one  side  and  the 
cheek  resting  firmly  against  a  plate  placed  on  a  book  about  three  or  four 
inches  thick  (  Fig.  330). 


Fig.    101.      Pose    for    the    radiograph    shown    in    Fig.    ion. 


Note  that  the  patient  is  covered  with  rubber  matting  such  as  is  used 
in  halls  and  on  stairways.  This  serves  as  an  insulator  to  keep  the  current 
from  jumping  to  the  patient's  body.  In  case  the  current  did  jump  to  the 
body  of  the  patient  a  blister  would  probably  be  made  at  the  point  of 
entrance  and  the  shock  would  be  more  or  less  painful,  but  not  dangerous. 

The  tube  is  of  course  insulated  from  the  metal  of  the  compression 
diaphragm.  An  additional  precaution  to  guard  the  patient  against  shock 
is  to  hook  a  chain — any  conductor,  in  fact — to  the  metal  of  the  compres- 
sion diaphragm  and  adjusting  apparatus  and  fasten  the  other  end  to  a 
chandelier,  gas  pipe  or  water  pipe.  With  this  arrangement,  if  any  cur- 
rent passes  into  the  compression  diaphragm  or  metal  adjusting-  apparatus 
it  will  follow  the  chain  into  the  gas  or  water  pipe,  and  on  to  where  the 


112 


DEXTAL  RADIOGRAPHY 


pipe  may  lead,  until   it  dissipates  itself,   eventually   reaching  the   earth, 
possibly.     This  is  called  "grounding-  the  current." 

While  it  is  always  host  to  have  the  patient  in  a  recumbent  position 
to  make  a  radiograph  such  as  Fig.  ioo.  it  is  not  necessary  to  use  a  special 


Fig.    102.     Pose    for   the    radiograph    shown    in    Fig.    103. 


cause  they  are  less  expensive  and  just  as  well  adapted  for  the  work. 
Plates  could  not  be  used  satisfactorily  inside  the  mouth,  because  they  will 
not  permit  the  slightest  bending.  Large  plate  radiographs  are  sadly 
lacking  in  detail  compared  to  those  made  on  films  held  in  the  mouth. 
radiographic  table  and  compression  diagram  as  is  shown  in  Fig.  101.  The 
patient  may  recline  on  the  ordinary  couch,  and  a  plain  tube  stand  used 
to  hold  the  tube.  Though  it  is  hardly  practical,  because  the  position  is 
50  awkward,  it  is  nevertheless  possible  to  take  radiographs  similar  to 
Fig.    ioo    without    having    the    patient    assume    the    recumbent    position. 

the  patient  on  a  -to..l  or  chair  and  have  him  lay  the  head  on  the 
plate,  which  i-  placed  on  a  stand  (Fig.  [02).  Fig.  103  is  a  radiograph 
made  from  a  pose  similar  to  Fig.  [02. 

Fig.    100  was  made  on  a  5\7-inch   plate.    Fig.    103  on  an  Xxio-inch 


M.IK  IXC  DENTAL  RADIOGRAPHS 


"3 


plate.  Plates  are  used  instead  of  films  for  these  large  radiographs  be- 
This  loss  of  detail  is  due,  not  to  the  fact  that  a  plate  instead  of  a  film 
is  used,  but  to  the  greater  distance  between  the  teeth  and  the  photographic 
emulsipn,  and  a  superimposition  of  shadows. 

The  most   popular  pose   for   taking   a   radiograph   of   the   antra   of 
Highmore  is  shown  in  Fig.  104,  and  the  radiograph  made  from  this  pose 


Fig.    103.      Radiograph   made   from   the   pose   shown   in   Fig.    102.      The   arrows   point   to   unerupted 

upper  and   lower   third   molars. 


in  Figs.  105  and  106.  This  radiograph  shows  also  the  frontal  sinuses 
and  the  ethmoidal  cells.  To  obtain  the  best  results  when  making  such  a 
picture  a  diaphragm  should  be  used.  To  avoid  unnecessary  straining  of 
the  tube  it  is  well  to  use  an  intensifying  screen.  Instead  of  using  the 
radiographic  table  and  having  the  patient  posed  as  in  Fig.  104.  the  patient 
may  assume  a  pose  similar  to  Fig.  98. 

A  picture  of  one  of  the  antra,  or  a  part  of  it.  may  be  made  on  a  film 


1  l-l 


DEXTAL   RADIOGRAPHY 


held  in  the  mouth,  the  pose  being  quite  similar  to  Fig.  85.  A  picture 
of  one  antrum  can  also  be  made  on  a  plate  by  a  modification  of  the  pose, 
shown  in  Figs.  101  and  102.     (Fig.  107.) 


Fig.    104.      Pose   for   making   radiograph   of  the   antra   of   Highmore. 


The  advantages  of  the  small  dental  radiographs 

fldcantafles  made  on  films  held  in  the  mouth  over  the  large  plate 

of  film  radiographs  are:     (i)   There  is  no  superimpositiorj 

Radiographs.  of   shadows,  and   therefore  a   clearer,  better  radio- 

graph    can    he    made    on    the    small    film.       (2)    The 

patient   may  1><    seated   in   the  dental  chair  while   the  exposure  is  made 

when  small  films  are  used.     (3)  The  time  of  exposure  is  shorter  for  the 

small  films.      (4)  Small  machines  with  which  it  is  necessary  to  make  an 


MAKING  DliXTAL  RADIOGRAPHS 


i'5 


Fig.    105.     Radiograph    made    from    the   pose   shown    in    Fig.    104.     A,    B,    frontal    sinuses.     C,    D, 

orbits.      E,    F,    ethmoidal    cells.      F   does    not    show   as    well    as    E    because    the    cells    of    this    side 

are    full    of    pus.      G,    H,    antra    of    Highmore.      I.    J.    nasal    cavity.     As    an    aid    in    reading    this 

radiograph   observe   Fig.   106.      (Radiograph  by  A.   M.   Cole,   of   Indianapolis.) 


exposure  of  one  minute  or  longer  for  large  plate  radiograph  will  make 
a  good  dental  radiograph  on  a  film  held  in  the  mouth  in  10  to  30  seconds. 
(5)  A  compression  diaphragm,  though  always  a  valuable  appliance,  is 
not  so  essential  when  small  films  are  used  as  it  is  when  large  plates  are 
used.      (6)  The  negative  on  celluloid  cannot  be  broken. 

The  great  advantage  of  the  large  plates  over  the  small  films  is  that 
a  larger  field  can  be  pictured. 


DENTAL   RADIOGRAPH 


Fig.    106.      -  16.     A,    frontal   sinuses.      B,   orbits.     <  .   ethmoidal   cells.      I),  antra. 

E,    nasal    cavities. 


Instead  of  using  a  photographic  plate  or  film  a 
Radiographs  radiograph   may   be  made   directly  on   photographic 

made  on  Paper.        paper.     This    paper    should    be    the    most    sensitive 
made,  so  that  the  exposure  will  be  as  short  as  possi- 
]>]<■.     Glossy  "bromide"  paper  is  the  hest.     Fig.   [08  illustrates  a  radio- 
graph of  the  hand  made  directly  on  bromide  paper.     (Reduced  one-half.) 
When   cutting  the   films   as  desired   and   covering  them    with   black 
paper — in  other  words,  when  making  the  film  packet — a  piece  of  bromide 


MAKING  DENTAL  RADIOGRAPHS  117 

paper  may  be  cut  the  same  size  and  shape  and  wrapped  up  with  the  film. 
The  paper  will  then,  of  course,  be  exposed  at  the  same  time  the  film  is, 
and  may  be  developed  also  at  the  same  time.    (Figs.  109  and  no.) 

After  making  a  radiograph  as  shown  in  Fig.  89,  it  may  be  trimmed 


Fig.    107.      The   more   or   less   oval    shadow   at   which    the   arrows    point   is   a    piece    of    tooth    root 
in    the   antrum.      (Radiograph    by    Carman,    of   St.    Louis,    Mo.) 


to  a  more  symmetrical  form.  In  other  words,  the  film  or  bromide  paper. 
as  wrapped  up  in  the  film  packet,  may  be  left  an  indefinite  unsymmetrical 
lorm  and  trimmed  to  a  more  pleasing  outline  after  the  picture  is  made. 
The  length  of  exposures  when  making  a  radiograph  directly  on  bromide 
paper  is  slightly  longer  than  when  using  a  film  or  plate.  Unlike  the  other 
sensitized  papers — Azo.  Yelox,  or  Cyko — the  bromide  paper  must  not  be 
exposed  to  the  orange  light.    The  light  must  be  the  same  as  for  films  and 


US 


DENTAL   RADIOGRAPHY 


plates,  a  ruby  light.     The  radiograph  made  directly  on  paper  lacks  good 
detail. 

Prints  from  negatives  may  be  made  on  bromide  paper.  The  advan- 
tage in  using  it  is  that  less  time  is  taken  up  in  making  exposures,  and  the 
disadvantage  is  that,  since  the  work  must  be  done  in  the  comparatively 
weak  ruby  light  instead  of  the  orange  light,  it  is  difficult  to  tell  just  when 
development  is  complete. 


Fig.  108.  Radiograph  made  on  bromide  paper.  The 
conditions  for  making  this  radiograph  were  exactly 
the  same  as  those  given  in  Chapter  IV  for  the 
negative  of  Fig.  71,  except  tin-  time  in  'lie  de- 
veloper,   which    was    about    100    seconds. 


Fig.  109.     Dental  radiograph  made 
directly   on   bromide   paper. 


Fig.  110.  The  negative  for  this 
radiograph  was  made  at  the  same 
lime  with  Fig.  109,  the  film 
being  enclosed  in  the  same  packet 
with    the    bromide    paper. 


Lantern  slides  may  easily  be  made  from  a  good 

Lantern  negative.     A   lantern   slide   plate   is   a  photographic 

Slide*.  plate  31/4x4  inches,  manufactured  especially  for  the 

purpose.   Like  all  other  photographic  plates,  it  should 

be  "worked"  in  the  ruby,  never  the  orange,  light.    The  negative  is  placed 

in  the  printing  frame,  sensitive  side  up.  and  the  slide  laid  over  it,  sensitive 


NOTE.— Fig,  no  appears  to  he  reversed.  This  is  due  to  the  fact  that  it  is  a 
print  from  tin-  film.  In  tin-  film  itself  the  teeth  would  appear  in  same  positions 
as  in  Fig.    109. — Ed. 


MAKING  DENTAL  RADIOGRAPHS  119 

side  down.  The  average  celluloid,  dental,  radiographic  negative  is  of  such 
density  that  the  time  of  exposure  of  the  plate  to  a  16-C.  P.  electric  light,  at 
a  distance  of  two  feet,  is  between  one  and  two  seconds.  Allow  the  slides 
to  remain  in  the  developer  a  few  seconds  after  the  radiograph  shows  best, 
until  it  shows  a  little  too  dark.  Wash  in  water  quickly  and  transfer  to 
the  fixing  bath,  where  it  should  remain  until  the  picture  shows  clearly 
as  desired.  The  writer  uses  Seed's  lantern  slide  plates  and  Seed's  pre- 
pared metol-hydrochinone  developer.  After  fixing,  the  slide  is  washed 
and  dried  the  same  as  any  photographic  plate.  When  dry  a  piece  of 
transparent  glass,  the  same  size  as  the  slide,  is  laid  on  the  film  side  of  the 
slide  and  the  two  stuck  together  at  their  edges  with  binding  tape,  such 
as  is  used  for  passe-partout  work.  The  piece  of  clear  glass  is  used  to 
protect  the  emulsion  of  the  slide  against  scratching. 

If  the  negative  from  which  the  slide  is  to  be  made  is  larger  than  the 
slide,  as  is  always  the  case  when  the  negative  is  on  glass,  the  work  had 
better  be  turned  over  to  a  professional  slide-maker. 

Dr.  Kells  makes  lantern  slides  of,  instead  of  from,  his  celluloid  den- 
tal negatives.    This  is  accomplished  as  follows : 

On  a  clear  glass  SlAx4  inches  place  a  piece  of  black  paper  the  same 
size,  with  a  hole  in  the  centre  large  enough  to  show  all  of  the  negative  that 
the  operator  wishes  to  exhibit.  Place  the  negative  directly  over  this 
hole  in  the  paper.  Place  another  piece  of  glass  3/4x4  inches  over  the 
whole  and  bind  the  two  pieces  of  glass  together  at  their  edges  with  bind- 
ing strips.  The  advantage  of  this  method,  over  making  photographic 
slides  are :  The  ease  and  dispatch  with  which  they  may  be  made — a 
dark  room  and  equipment  is  not  necessary — and,  since  we  are  using  the 
negative  itself,  there  is  no  loss  of  detail  such  as  might  occur  when  the 
other  method  is  employed  and  a  new  picture  is  made  on  the  photo- 
graphic slide.  The  disadvantage  is  that  the  negatives  with  good  detail 
are  usually  so  dark  that  the  light  from  the  lantern  is  not  strong  enough 
to  penetrate  them. 

That  the  student  of  dental  radiography  may  learn  the  different  con- 
ditions under  which  radiographs  of  the  teeth  and  jaws  are  made,  I  give 
the  following  summaries  in  which  are  recorded  the  important  factors. 

The  summaries,  in  the  order  in  which  they  follow,  to  and  including 
Fig.  115,  represent  some  experimental  work  done  by  the  writer.  These 
reports,  like  most  reports,  make  very  dry  reading,  but  they  contain  some 
information  of  importance.  A  study  of  the  summaries  for  Figs.  81. 
in,  97,  99  and  103,  will  give  a  tolerably  good  idea  of  what  can  be  done 
with  an  induction  coil.  A  study  of  the  summaries  for  Figs.  112,  113 
114  and  115  will  give  an  idea  of  what  can  be  accomplished  with  a  small, 
suitcase,  high-frequency  coil. 


120 


DENTAL   RADIOGRAPHY 


A  careful  reading  of  the  "comment"  at  the  close  of  some  of  the 
summaries  is  especially  advised,  because  therein  will  be  found  some 
valuable  pointers. 

To  make  the  negative  of  the  radiograph  shown 
Tig.  81.  in  Fig.  81   the  conditions  were  as   follows: 

I.  Machine  used:  A  Scheidel,  18-inch,  induction 
coil  with  2-point,  electrolytic  interrupter,  operating  on  a  no-volt  D.  C. 
circuit.     All  the  resistance  of  the  rheostat  cut  out. 


Fig.    111.     The   two   circular    shadows   in    the   corners   are   due   to   small    paper   clips   used    to   hold 
the   intensifying    screen   and    film    together. 


2.  Strength  of  current :  Xo  meters  on  machine.  A  rough  guess 
would  be  26  amperes  in  the  primary,  about  13  milliamperes  sent  through 
the  tube.     Ten  ( 10)   inches  of  fat,  fuzzy,  yellow  spark  obtainable. 

3.  Make  and  condition  of  tube  used:  Green  and  Bauer,  "Clover- 
leaf,"  6-inch  tube.  Length  of  tube-regulating  spark  gap,  3^  inches. 
Tube  backs  up  7  inches  parallel  spark.  The  tube  vacuum  is  therefore 
high,  and  the  X-rays  produced  penetrating.     Xo  penetration  guide  used. 

4.  Distance  of  target  from  film:  Between  12  and  13  indies.  Distance 
of  glass  of  tube  from  face,  about  8  inches. 

5.  Thickness  of  part :  That  of  superior  maxillary  bone  and  over- 
lying tissues,  about  il/2  inches. 

6.  Density  of  part:  That  of  superior  maxillary  bone  and  overlying 
tissues.     ( Density  varies  slightly  with  age,  growing  denser.) 

7.  Film  used:     Eastman  f positive  cinematographic)  X-ray  film. 

8.  Time  of  exposure:     Eight  (8)  seconds. 

<).  Time  in  the  developer,  and  developer  used:  Five  (5)  minutes  in 
Eastman's  "M.  O."  prepared  developer. 


MAKING  DENTAL  RADIOGRAPHS  121 

Comment:  When  using  an  Ilford  film  the  exposure  can  be  reduced 
one-half,  *.  c,  to  4  seconds,  and  the  time  in  the  developer  remains  5  min- 
utes. The  negative  of  Fig.  83  was  made  on  an  Ilford  film,  exposure  4 
seconds. 

It  will  not  be  amiss  here  to  give  my  readers  some  idea  of  how  T 
"guessed"  at  the  amperage  and  milliamperage,  respectively,  of  my  pri- 
mary and  secondary  currents.  The  fuses  just  in  front  of  my  coil  are 
30  ampere  fuses.  I  know,  therefore,  that  I  am  drawing  something  less 
than  30  amperes.  I  know  also  that  I  must  be  drawing  almost  30  amperes 
with  all  the  resistance  of  the  rheostat  out,  and  I  make  a  rough  guess  of 
26,  leaving  a  margin  of  4  amperes  between  the  current  I  am  using  and 
one  which  would  "blow"  (burn)  the  fuses.  Having  guessed  at  the  am- 
perage, I  calculate  that  the  average  induction  coil  is  capable  of  forcing 
one-half  as  many  milliamperes  through  a  high  vacuum  tube  as  it  draws 
amperes  in  its  primary.  Thus,  if  the  coil  draws  26  amperes  the  milliam- 
perage output  through  a  high  vacuum  tube  is  13. 

A  high  frequency  coil  is  capable  of  forcing  two-thirds  as  many  mil- 
liamperes through  a  high  tube  as  it  draws  amperes  in  its  primary,  and  the 
interrupterless  coil  can  force  about  four-fifths  as  many  milliamperes 
through  a  high  tube  as  it  draws  amperes  into  its  primary.  This  is  only 
an  estimate,  not  a  mathematical  fact. 

To  make  the  negatives  of  the  radiagraph  shown 
fig.  111.  in  Fig.  1 1 1  the  conditions  were  as  follows  : 

1.  Machine  used:    Same  as  for  Fig.  81. 

2.  Strength  of  current:     Same  as  for  Fig.  81. 

3.  Make  and  condition  of  tube:     Same  as  for  Fig.  81. 

4.  Distance  of  target  from  film:  About  13  inches.  Distance  from 
glass  of  tube  to  patient's  face,  about  8  inches.    Pose  as  in  Fig.  89. 

5.  Thickness  of  part:    Same  as  in  Fig.  81. 

6.  Density  of  part:    Same  as  in  Fig.  81. 

7.  Film  used :  Ilford  film,  with  a  Kny-Scheerer  intensifying  screen. 
(I  wish  to  thank  the  Kny-Scheerer  Mfg.  Co.  for  their  kindness  in  making 
a  dental  intensifying  screen  after  my  instructions,  and  furnishing  me  with 
samples  for  experimental  purposes.) 

8.  Time  of  exposure  :     One  ( 1 )  second. 

9.  Time  in  the  developer,  and  developer  used:  Four  (4)  minutes 
in  the  Eastman  "M.  Q."  developer. 

Comment:  Had  the  intensifying  screen  not  been  used,  the  time  of 
exposure  would  have  been  about  four  (4)  seconds.  Thus  the  use  of  the 
screen  shortened  the  time  of  exposure  necessary  three-fourths   (^4). 

To  make  the  negatives  of  Fig.  97  the  conditions 
Tifl.  97.  were  as  follows : 

1.  Machine  used:   Same  as  for  Figf.  81. 


122  DENTAL   RADIOGRAPHY 

2.  Strength  of  current:     Same  as  for  Fig.  81. 

3.  Make  and  condition  of  tube:     Same  as  for  Fig.  81. 

4.  Distance  of  target  from  film:  About  14  inches.  Distance  of 
glass  of  tube  from  face,  about  8  inches.     Pose  as  in  Fig.  97. 

5.  Thickness  of  part:  Tissues  of  neck,  mandible  and  overlying 
parts — about  3  inches. 

6.  Density  of  part :  That  of  tissues  of  neck,  mandible  and  overlying 
parts. 

7.  Film  used :    Ilford  film. 

8.  Time  of  exposure :     Thirty-five  (35)  seconds. 

9.  Time  in  the  developer,  and  developer  used:  Five  (5)  minutes  in 
Eastman  "M.  O."  developer. 

To  make  the  negative  of  the  radiograph  shown 
fig.  $9.  in  Fig.  99  the  conditions  were  as  follows : 

1.  Machine  used:    Same  as  for  Fig.  81. 

2.  Strength  of  current:     Same  as  for  Fig.  81. 

3.  Make  and  condition  of  tube:     Same  as  for  Fig.  81. 

4.  Distance  of  target  from  film:  About  16  inches.  Distance  of 
glass  of  tube  from  patient's  neck,  about  8  inches.    Pose  as  in  Fig.  98. 

5.  Thickness  of  part:  That  of  the  tissues  of  the  neck,  the  mandible 
and  overlying  parts — about  5  inches. 

6.  Density  of  part :  That  of  the  tissues  of  the  neck,  mandible  and 
overlying  tissues. 

7.  Film  used :  Lumiere,  "Sigma,"  double-coated,  5x7~inch  X-ray 
plate. 

8.  Time  of  exposure:    Thirty-five  (35)  seconds. 

9.  Time  in  developer,  and  developer  used:  Fifteen  (15)  minutes  in 
Eastman  "M.  Q."  developer. 

To  make  the  negative  of  the  radiograph  shown 
fig.  103.  in  Fig.  103  the  conditions  were  as  follows: 

I.  Machine  used:    Same  as  for  Fig.  81. 

2.  Strength  of  current:     Same  as  for  Fig.  81. 

3.  Make  and  condition  of  tube:    Same  as  for  Fig.  81. 

4.  Distance  of  target  from  plate:  Between  12  and  13  inches.  Dis- 
tance of  glass  of  tube   from  patient's   face  and  neck,  about  6  inches. 

I  This  is  bringing  the  tube  about  as  close  to  the  patient  as  it  can  be  placed 
with  safety.)     Pose  similar  to  Fig.  102. 

5.  Thickness  of  part :  That  of  the  tissues  of  the  neck,  the  mandible 
and  overlying  tissues  for  the  lower  jaw,  and  the  cheek,  the  superior 
maxillary  bone  and  overlying  tissues  for  the  upper  jaw — 3  to  4  inches. 

6.  Density  of  part:     As  above,  under  "thickness  of  part." 


MAKING  DENTAL  RADIOGRAPHS  123 

7.  Plate  used:  Lumiere,  "Sigma,"  double-coated,  8xio-inch  X-ray 
plate. 

8.  Time  of  exposure :    Forty-five  (45)   seconds. 

9.  Time  in  the  developer,  and  developer  used:  Ten  (10)  minutes 
in  the  Eastman  "M.  Q."  developer. 

Comment:  After  such  an  exposure  the  tube  would  be  very  warm, 
and  should  be  allowed  to  cool  thoroughly  before  using  again. 

The  rule  to  allow  the  film  or  plate  to  remain  in  the  developer  twenty 
times  as  long  as  it  takes  the  high  lights  to  show  up  well  is  often  inap- 
plicable when  developing  these  large  pictures  on  plates.  It  is  sometimes 
necessary  to  leave  the  plate  in  the  developer  thirty  or  forty  times  as 
long  as  it  takes  the  high  lights  to  appear.  Allow  the  plate  to  remain  in 
the  developer  until  almost  all  black — not  jet  black,  but  darkened  well. 
It  is  difficult  to  the  point  of  being  impossible,  usually,  to  see  the  image 
while  the  plate  is  in  the  developer ;  only  an  obscure  suggestion  of  the 
radiograph  can  be  seen. 

Had  the  negative  for  Fig.  103  been  left  in  the  developer  but  5  or 
6  minutes  instead  of  10,  or  had  the  exposure  been  made  slightly  shorter, 
say  40  seconds,  then  the  outline  of  the  mandible  would  not  be  lost,  as  it  is. 

To  make  the  negative  of  the  radiograph  shown 
Tifl.  100.  in  Fig.  100  the  conditions  were  as  follows : 

1.  Machine  used:  Kelly-Koett,  "Grosse- 
Flamme,"  induction  coil  on  third  inductance,  with  7-point  electrolytic  in- 
terrupter, operating  on  a  no- volt  D.  C.  circuit. 

2.  Strength  of  current:  Primary  about  40  amperes.  Milliamper- 
age  sent  through  tube,  about  20.  Fat,  fuzzy  spark  obtainable  full  length 
of  spark  gap,  12  inches. 

3.  Make  and  condition  of  tube:  Green  and  Bauer,  "Cloverleaf" 
6-inch  tube.  Length  of  tube  regulating  spark  gap,  about  4^  inches. 
Tube  backs  up  7  or  8  inches  of  parallel  spark. 

4.  Distance  of  target  from  plate:    About   16  inches. 

5.  Thickness  of  part:     See  Fig.  101. 

6.  Density  of  part :  That  of  tissues  of  the  neck,  mandible  and  over- 
lying parts  for  the  lower  jaw,  and  superior  maxillary  bone  and  overlying 
parts  of  the  upper  jaw. 

7.  Plate  used :     Lumiere,  X-ray  plate,  5x7  inches. 

8.  Time  of  exposure:     Ten   (10)   seconds. 

9.  Time  in  developer,  and  developer  used:  Five  (5)  minutes  in 
"M.  Q."  prepared  developer. 

Comment :  The  Kelly-Koett,  Gross-Flamme,  coil  is  one  of  the  most 
powerful  induction  coils  made. 


124 


DENTAL   RADIOGRAPHY 


To  make  the  negative  of  the  radiograph  shown 
fig.  ios.  in  Fig.   105  the  conditions  were  as  follows: 

1.  Machine  used:  Kelly-Koett,  "Gross-Flamme"' 
induction  coil  on  inductance  four,  with  7-point  electrolyte  interrupter, 
operating  on  110-volt  D.  C.  circuit. 

2.  Strength  of  current:  Primary,  50  amperes.  Milliamperes  sent 
through  tube,  about  25. 

3.  Make  and  condition  of  tube:  Green  and  Bauer,  "Cloverleaf"  6- 
inch  tube.  Length  of  tube  regulating  spark  gap,  5  inches.  Tube  backs 
up  8  inches  of  parallel  spark. 


Fig.    112. 


4.  Distance  of  target  from  plate:     About  19  inches. 

5.  Thickness  of  part:  That  of  the  cranium  coverings  and  con- 
tents, about  8  inches.     (Fig.  104.) 

6.  Density  of  parts:     That  of  the  cranium,  coverings  and  contents. 

7.  Plate  used:  Cramer  X-ray  plate,  8x10  inches,  with  intensifying 
screen. 

8.  Time  of  exposure:     Three  (3)   seconds. 

9.  Time  in  developer,  and  developer  used:  Seven  (7)  minutes 
in  water,  32  oz. ;  soda  sulphite,  12  dr.;  hydrochinone,  2  dr.;  edinol,  75 
gr. ;  potassium  bromide,  90    gr. ;  potassium  carbonate,  2  oz. 

Comment:  Had  an  intensifying  screen  not  been  used,  the  time  of 
exposure  would  have  been  about  ten  (10)  seconds. 

To  make  the  negative  of  the  radiograph  shown 
Tig.  112.  in  Fig.  112  the  conditions  were  as  follows: 

I.  Machine  used:  Scheidel-Western,  portable 
high-frequency,  6-inch  coil,  operating  on  [04-volt  A.  C.  circuit.  (  ['  wish 
to  acknowledge  my  indebtedness  and  express  my  sincere  thanks  to  the 
Scheidel-Western  X-ray  Coil  Mfg.  Co.,  who  furnished  me  with  their 
coil   for  experimental   work.) 


MAKING  DENTAL  RADIOGRAPHS 


I25 


Fig. 


113.     Arrow   A  points  to   an   impacted  lower   third   molar.     Arrow   B   points   to   the   temporo- 
mandibular   articulation,    which    shows    very    clearly    in     this    picture. 


IJt. 


DENTAL   RADIOGRAPHY 


2.  Strength  of  current:  No  meters.  A  rough  guess,  12  amperes  in 
primary.  Milliamperage  sent  through  tube,  about  8.  Fat,  fuzzy  spark 
6  inches  long  obtainable. 

3.  Make  and  condition  of  tube:  Green  and  Bauer,  6-inch,  high-fre- 
quency tube.  Tube-regulating  spark  gap,  5  inches.  (In  my  limited  ex- 
perience I  have  found  that  the  tube-regulating  spark  gap  must  be  longer 
for  higl -frequency  tubes  to  obtain  the  same  condition  of  vacuum.)  Tube 
backs  up  6  inches  of  parallel  spark. 


Fig.    114. 


4.  Distance  of  target  from  film:  Between  11  and  12  inches.  Dis- 
tance between  glass  of  tube  and  patient's  face,  about  7  inches. 

5.  Thickness  of  part :  That  of  superior  maxillary  bone  and  overly- 
ing tissues. 

6.  Density  of  part :  That  of  superior  maxillary  bone  and  overlying 
tissues. 

7.  Film  used:     Ilford  X-ray  film. 

8.  Time  of  exposure:     Ten  (10)  seconds. 

9.  Time  in  developer:     Five  (5)  minutes  in  "M.  Q."  developer. 
Comment :     Flow  can  a  tube  backing  up  6  inches  of  parallel  spark 

be  operated  by  a  coil  the  terminals  of  which  are  only  6  inches  apart? 
is  a  natural  and  fair  question.  This  is  accomplished  by  placing  an  up- 
right piece  of  plate-glass  between  the  terminals  of  the  coil,  which  pre- 
vents sparking  between  them. 

With  conditions  as  above,  an  exposure  of  about  20  seconds  is  neces- 
sary when  Eastman  films  are  used. 

Be  it  understood  that  [O  seconds  for  Ilford  films  and  20  seconds  for 
Eastman  films  do  not  represent  the  minimum  exposures  for  the  making 
of   dental    radiographs   under   the   conditions   as   above.     For  example,  I 


MAKING  DENTAL  RADIOGRAPHS 


127 


rig.   115.     Arrow  A  points  to  an   unerupted  lower   third   molar.      Arrow    B   points  to  the   temporo- 
mandibular   articulation,    which    shows    very    clearly    in    this    radiograph.       The    triangular    spot 
marked    C    is    the    result    of    not    completely    covering   the    plate    immediately    when    it    was    placed 

in     the     developer. 


I28  DENTAL   RADIOGRAPHY 

was  able  to  obtain  a  tolerably  good  radiograph  after  a  io-seconds  ex- 
posure on  an  Eastman  film  by  leaving  it  in  the  developer  14  minutes.  To 
obtain  the  best  pictures,  however,  the  exposure  should  be  10  seconds  for 
Ilford  film-  and  20  seconds  for  Eastman  films. 

To  make  the  negative  of  the  radiograph  shown 
fig.  113.  in  Fig.  113  the  conditions  were  as  follows: 

1.  Machine  used:     Same  as  for  Fig.  112. 

2.  Strength  of  current:     Same  as  for  Fig.  112. 

3.  Make  and  condition  of  tube:    Same  as  for  Fig.  112. 

4.  Distance  of  target  from  plate:  Between  12  and  13  inches.  Dis- 
tance of  glass  of  tube  from  patient's  face  and  neck,  6  inches.  Pose 
similar  to  Fig.  102. 

5.  Thickness  of  part :  That  of  tissues  of  the  neck,  mandible  and 
overlying  parts  for  the  lower  jaw,  and  the  superior  maxillary  bone  and 
overlying  parts  for  the  upper  jaw — 3  to  4  inches. 

6.  Density  of  part :     As  above  under  "thickness  of  part." 

7.  Plate  used:  Lumiere,  "Sigma/'  double-coated,  8xio-inch  X-ray 
plate. 

8.  Time  of  exposure:     Sixty   (60)  seconds. 

9.  Time  in  the  developer  and  developer  used:  Seven  (7)  minutes 
in  Eastman  "M.  Q."  developer. 

Comment :  The  tube-regulating  spark  gap  was  set  at  a  distance  of 
5  inches,  or  perhaps  a  little  longer,  and  at  no  time  did  the  current  jump 
the  gap.  Theoretically,  as  the  current  passes  through  the  tube  the 
vacuum  becomes  higher.  I  was  considerably  surprised,  therefore,  to  ob- 
serve after  the  current  had  been  passing  through  the  tube  for  about  50 
seconds  that  the  blue  cathode  stream  could  be  seen,  indicating  a  very 
low  vacuum.  My  friend,  Mr.  Darling,  a  designer  of  coils,  informs  me 
that  this  lowering  of  the  vacuum  is  due  to  heating  of  the  tube.  The  milli- 
amperage  sent  through  it  heats  the  entire  tube,  which  means,  of  course, 
that  the  regulating  chamber  and  its  contents  are  heated,  gases  from  the 
regulating  chamber  are  liberated,  and  so  the  vacuum  is  lowered,  without 
at  any  time  a  spark  occurring  at  the  tube-regulating  spark  gap. 

It  is  well  to  mention  here,  perhaps,  that  there  is  very  often  a  blue 
color  bark  of  the  target  in  high-frequency  tubes,  which  does  not  signify 
a  low  vacuum.  However,  when  a  blue  cathode  stream  can  be  seen,  or 
when  there  are  areas  of  blue  in  any  part  of  the  active  hemisphere,  it  sig- 
nifies a  vacuum  too  low  for  good  picture  work. 

To  make  the  negative  of  the  radiograph  shown 
fig.  )|4.  in  Fig.   114  the  conditions  were  as  follows: 

1.  Machine   used:      Scheidel-Western,   portable 
high-frequency,  6-inch  coil,  operating  on  a  70-volt  A.  C.  circuit  generated 


MAKING  DENTAL  RADIOGRAPHS 


129 


by  a  rotary  converter.     The  rotary  converter  being  set  in  motion  by  the 
commercial   no-volt  D.  C. 

2.  Strength  of  current:  The  primary  current  furnished  by  the  con- 
verter, about  5  amperes.  Milliamperage  sent  through  tube,  3  or  a  little 
over.  A  tolerably  fat,  fuzzy  spark  four  (4)  inches  long  obtainable.  The 
spark,  instead  of  being  white  or  yellow  as  when  the  milliamperage  is 
high,  is  of  a  blue  or  purplish  color. 


Fig.    116.      Diagram    of   portable,    high-frequency    coil. 


Six   (6)   minutes  in 


3.  Make  and  condition  of  tube:    Same  as  for  Fig.  112. 

4.  Distance  of  target  from  plate:   Same  as  for  Fig.  112. 

5.  Thickness  of  part:     Same  as  for  Fig.- 112. 

6.  Density  of  part:     Same  as  for  Fig.  112. 

7.  Film  used :     Ilford  X-ray  film. 

8.  Time  of  exposure:     Fifteen  (15)  seconds. 

9.  Time  in  the  developer  and  developer  used : 
the  Eastman  "M.  Q."  developer. 

Comment :  Because  of  the  considerable  difference  in  the  milliam- 
perage sent  through  the  tube  it  might  be  expected  that  there  would  be 
an  increase  in  the  time  of  exposure  necessary  when  operating  the  high- 
frequency  coil  from  a  rotary  converter.  Using  the  same  coil,  the  time 
of  exposure  when  the  coil  is  excited  by  the  rotary  converter  should  be, 
to  obtain  the  same  results,  about  one-half  longer  than  when  the  coil  is 
operating  from  the  commercial  104-volt  A.  C. 

To  make  the  negatives  of  the  radiograph  shown 
fig.  us.  in  Fig.  115  the  conditions  were  as  follows: 

1.   Machine  used:     Same  as  for  Fig.   112. 

2.  Strength  of  current:     Same  as  for  Fig.  112. 

3.  Make  and  condition  of  tube:     Same  as  for  Fig.  112. 

4.  Distance  of  target  from  plate:     Between  12  and  13  inches.     Dis- 


i3o  DENTAL  RADIOGRAPHY 

tance  of  glass  of  tube  from  patient's  face,  about  6  inches.     Pose  similar 
to  Fig.  102. 

5.  Thickness  of  part :  That  of  the  tissues  of  the  neck,  the  mandible 
and  overlying  parts  for  the  lower  jaw,  and  the  superior  maxillary  bones 
and  overlying  parts  for  the  upper  jaw. 

6.  Density  of  part :    As  given  under  "thickness  of  part." 

7.  Plate  used:  Lumiere,  "Sigma,"  double-coated,  8xio-inch  X-ray 
plate. 

8.  Time  of  exposure:     Seventy-two  (72)  seconds. 

9.  Time  in  the  developer,  and  developer  used :  Fourteen  (14)  min- 
utes in  the  Eastman  "M.  O."  developer. 

Comment :  When  the  time  of  exposure  is  so  long,  72  seconds,  as  in 
this  case,  the  matter  of  a  couple  of  seconds  or  so  makes  little  or  no 
difference.  That  is  to  say,  the  time  of  exposure  might  have  been, 
say,  70  or  75  seconds,  and  the  same  results  obtained  as  with  an 
exposure  of  J2  seconds ;  and  this  without  altering  the  time  in  the 
developer.  When  developing  an  especially  sensitive  plate,  such  as  the 
one  used  in  this  case,  the  Lumiere  "Sigma"  plate,  for  a  considerable 
length  of  time  it  is  not  expedient  to  keep  it  constantly  exposed  to  the 
ruby  light.     Fogging  might  result. 

It  will  be  noticed  that  to  make  this  negative  the  time  of  exposure 
was  only  one-fifth  longer  than  to  make  the  negative  for  Fig.  113.  Ac- 
cording to  my  remarks  under  the  heading  "Comment"  in  the  summary 
of  the  conditions  under  which  Fig.  114  was  made,  the  exposure  should 
have  been  "about  one-half  longer  to  obtain  the  same  results."  But 
notice,  please,  that  it  was  necessary  to  leave  the  plate  for  Fig.  115  in  the 
developer  twice  as  long  as  for  Fig.  113.  Therefore,  I  did  not  get  the 
same  results  when  I  increased  my  exposure  only  one-fifth. 

There  are  two  or  three  special  and  important 

technic  for  points  concerning  the  operation  of  a  high-frequency 

Use  Of  High-  coil  that  I  shall  mention  here : 

frequency  Coil.  First,  move  the  lever  at  the  back  of  the  coil  onto 

the  button  marked  "low  frequency"  (sometimes 
"X-rays") — off  of  the  button  marked  "high  frequency."  (Fig.  116.)  By 
doing  this  all  of  the  condenser  of  the  coil  is  used,  and  so  the  rate  of 
frequency  lessened.  For  high-frequency  treatment  work  only  a  part  of 
Lhe  condenser  i-  used,  with  the  lever  arm  on  the  button  marked  "high 
frequency." 

md,  <-ut  out  all  the  resistance  of  the  rheostat,  separate  the  sliding 
rod  or  rod-  to  the  maximum  spark  gap — usually  about  6  inches — and 
turn  on  the  current. 

Third,  widen  and  narrow  the  "regulating  spark  gap"  until  the  cur- 


M.IK  IXC  DENTAL  K.  IDIOGR.  WHS 


131 


rent  is  as  high  in  milliamperage  as  it  can  be  and  still  jump  the  terminal 
spark  gap.  It  will  be  remembered  that  widening  the  regulating  spark 
gap  (up  to  a  certain  point)  increases  the  voltage  of  the  output  current 
at  the  expense  of  the  milliamperage,  and  that  narrowing  it  increases  the 
milliamperage  at  the  expense  of  the  voltage.  Alter  the  regulating  spark 
gap  to  get  as  heavy  a  spark  as  possible.  It  should  require  but  a  few  sec- 
onds to  accomplish  this  regulation.  Sometimes  it  is  impossible  to  obtain 
as  fuzzy  a  spark  as  you  know  the  machine  is  capable  of  giving.  This  is 
due  to  the  fact  that  the  little  approximating  metal  studs  at  the  regulating 


Fig.    117.      Radiograph   by   Peabody,   of   South   Orange.    X.   J. 


spark  gap  are  dirty.  Place  a  piece  of  emery  cloth  between  the  studs, 
screw  them  together  until  they  hold  the  cloth  loosely,  then  draw  the 
cloth  back  and  forth  over  the  face  of  the  stijd.  Clean  both  studs  in  this 
way. 

Fourth,  place  a  piece  of  plate  glass  between  the  terminals  in  order 
that  a  high  vacuum  tube,  one  with  a  resistance  equivalent  to  6  or  more 
inches  of  parallel  spark,  may  be  used. 

Fifth,  connect  the  tube  to  the  coil,  set  the  tube-regulating  spark  for 
about  5  inches,  turn  on  the  current  and  see  that  the  tube  lights  up  O.  K. 

I  recall  and  shall  here  set  forth  an  experience 
J\ti  Instructive  I  had  while  making  a  radiograph  on  a  large  plate 

Experience.  with   a  small,  high-frequency  coil.      I   had  followed 

the  technic  given  above,  posed  my  patient,  and 
turned  on  the  current  for  a  one-minute  exposure.  For  the  first  thirty- 
five  seconds  the  tube  maintained  a  good  light.  Then  suddenly  the  cur- 
rent ceased  to  pass  through  it.  At  first  I  thought  I  had  burned  out  a 
fuse.  (I  was  using  15-ampere  fuses  on  the  supply  wires  to  protect  the 
coil.)  But  by  turning  the  switch  on  and  off  I  learned  that  in  this  surmise 
I  was  wrong,  for  when  the  switch  was  on  there  was  a  humming  sound 
in  the  coil,  and  as  I  turned  it  off  a  spark  occurred  as  the  circuit  was 
broken.     I  shortened  the  tube-regulating  spark  gap,  thinking  perhaps  the 


132  DENTAL   RADIOGRAPHY 

vacuum  in  the  tube  had  suddenly  and  mysteriously  become  so  high  that 
the  current  could  not  pass  through  it,  but  when  the  current  was  turned 
on,  the  only  evidence  of  the  fact  was  a  slight  humming  inside  the  coil. 

I  disconnected  the  tube,  removed  the  plate  glass  from  between  the  ter- 
minals and  turned  on  the  current,  but  no  spark  jumped  the  gap.  Not  un- 
til then  did  I  realize  that  the  trouble  was  at  the  regulating  spark  gap.  I 
changed  the  adjustment  of  the  gap  slightly  and  immediately  a  spark 
jumped  the  terminal  spark  gap.  The  metal  at  the  regulating  spark  gap 
had  gotten  warm  and  expanded,  thus  altering  the  width  of  the  gap  and 
shutting  off  the  current. 

With  two  exceptions,  all  the  summaries  of  conditions  under  which 
radiographs  are  made  have  been  records  of  my  own  work.  (These  two 
exceptions  are  Fig.  ioo,  made  by  Dr.  A.  M.  Cole  and  myself,  and  Fig.  105, 
made  by  Dr.  Cole.)  That  my  readers  may  have  some  idea  of  the  govern- 
ing circumstances  under  which  other  men  make  radiographs,  I  print  the 
following  summaries.  For  the  report  and  radiographs  we  are  indebted 
to  the  men  whose  names  appear  beneath  the  radiographs. 

To  make  the  negative  of  the  radiograph  shown 
Usinq  an  m  ^ig-  1:7  tne  conditions  were  as  follows: 

Tnterrupterless  I-  Machine  used:    Kny-Scheerer  interrupterless 

Coil.  coil.      Four    and    one-half    kilowatts.      Eleven-inch 

spark  gap.     Operating  on  104-volt  A.  C.  circuit. 

2.  Strength  of  current:  Primary,  50  amperes.  Milliamperage  sent 
through  tube,  40.     Fat,  fuzzy  spark  obtainable  full  length  of  spark  gap, 

II  inches. 

3.  Make  and  condition  of  tube:  Machlett  tube,  Excelsion  brand. 
Tube  backs  up  about  6  or  7  inches  of  parallel  spark.  Penetration  of 
X-rays,  8  Wehnelt,  which  is  the  same  as  6  Walter.    Very  penetrating. 

4.  Distance  of  target  from  film:     About  12  inches. 

5.  Thickness  of  part :  That  of  superior  maxillary  and  overlying 
tissues. 

6.  Density  of  part :  That  of  superior  maxillary  and  overlying 
tissues. 

7.  Make  of  film:     Eastern  X-ray  film. 

8.  Time  of  exposure  :     One  ( 1 )  second. 

9.  Time  in  developer  and  developer  used:  Five  (5)  minutes.  For- 
mula not  given. 

Comment:  "Four  and  one-half  killowatts"  expresses  the  rating  of 
the  machine.     <  haptcr  1 1. 

Had  an  [lford  film  been  used  instead  of  an  Eastman,  the  time  of 
exposure   would   have  been  one-quarter  second.      It   will  be  noticed  that 


MAKING  DENTAL  RADIOGRAPHS 


133 


Dr.  Peabody  considers  the  Ilford  film  four  times  as  fast  as  the  Eastman, 
while  my  own  experience  leads  me  to  believe  that  it  is  only  about  twice 
as  sensitive. 

When  making  exposures  that  necessitate  the   splitting  of   seconds, 
an  automatic  switch  timer  may  be  used  to  advantage. 

To  make  the  negative  of  the  radiograph  shown 
ffg.  ii$  in  Fig.   118  the  conditions  were  as  follows: 

1.  Machine  used:  A  Ritchie,  10-inch  induction 
coil,  with  i-point  electrolytic  interrupter,  operating  on  a  uo-volt  D.  C. 
circuit. 

2.  Strength  of  current:     Fat,  fuzzy  spark  10  inches  long  obtainable. 


Fig.     118.     By    Lodge,    of    Cleveland,    O. 


3.  Make  and  condition  of  tube :  Hartford,  7-inch  tube.  Length  of 
tube-regulating  spark  gap,  3^  inches.  The  tube  backs  up  four  (4)  inches 
of  parallel  spark. 

4.  Distance  of  target  from  film :     Ten  ( 10)  inches. 

5.  Thickness  of  part :  That  of  superior  maxillary  and  overlying 
tissues. 

6.  Density  of  part :  That  of  superior  maxillary  and  overlying  tis- 
sues.    Patient  12  years  old. 

7.  Film  used :    Eastman  dental  film. 

8.  Time  of  exposure.     Six  (6)  seconds. 

9.  Time  in  the  developer  and  developer  used :  Ten  minutes  in : 
Solution  A,  Water,  64  oz. ;  metol,  120  grs. ;  hydrochinon,  120  grs. ;  Seed's 
sulphite  of  soda,  2  oz.  Solution  B,  water,  16  oz. ;  Seed's  carbonate  of 
soda,  2  oz.    For  use  take  of  A,  4  oz. ;  of  B,  1  oz.,  and  of  water,  4  oz. 

To  make  the  negative  of  the  radiograph  shown 
fig.  119.  in  Fig.  119  the  conditions  were  as  follows: 

1.  Machine  used:  Scheidel- Western,  12-inch 
induction  coil,  with  electrolytic  interrupter,  operating  on  a  uo-volt  D.  C. 
circuit. 


*34 


DENTAL   RADIOGRAPHY 


2.  Strength  of  current:    Eighteen  (18)  or  twenty  (20)  milliamperes 
sent  through  tube. 

3.  .Make   and   condition  of   tube:      Green   and    Bauer   "Cloverleaf." 
Length  of  tube-regulating  spark  gap :    2l/2  inches. 

4.  Distance  from  target  to  him:     About  18  inches. 

5.  Thickness  of  part:     That  of  the  body  of  the  mandible  and  over- 
lying tissues. 

6.  Density  of  part      That  of  the  body  of  the  mandible  and  overlying 
tissues. 

7.  Film  used :     Seed's  special  X-ray  film. 

8.  Time  of  exposure :     About  6  seconds. 


Fig.    119.      By    Ketcham,    of    Denver,    Colo. 


Fig.     120.     By     Blum,     of     New     York. 


9.  Time  in  developer  and  developer  used :  About  20  minutes  in : 
Sodium  sulphite,  3  oz. ;  potassium  carbonate,  2  oz. ;  eikogen,  2  oz. ; 
water,  2  quarts.  Dissolve  in  boiling  water  and  filter  when  cool.  Take 
one  part  of  the  developer  to  three  parts  of  water  for  use. 

To  make  the  negative  of  the  radiograph  shown 
Tig.  120.  in  Fig.  120  the  conditions  were  as  follows: 

1.  Machine  used:  A  Wrappler  12-inch  induction 
coil,  with  2-point,  electrolytic  interrupter,  operating  on  a  1 10-volt  D.  C. 
current. 

2.  Strength  of  current:  Twenty-five  12^)  amperes  in  the  primary. 
About  9  inches  of  fat,  fuzzy  spark  obtainable. 

3.  Make  and  condition  of  tube:  Muller,  water-cooled.  Penetration 
about  7  Benoist.     Length  of  tube-regulating  spark  gap.  3^  inches.    Tube 

•  6  i"  7  inches  of  parallel  spark. 

4.  Distance  of  target  from  film:    About  14  inches. 

5.  Thickness  of  part:  Thai  of  superior  maxillary  bone  and  over- 
lying 

6.  Densit)  of  part:    That  of  superior  maxillary  bone  and  overlying 


MAKING  DENTAL  RADIOGRAPHS 


135 


7.  Film  used:  Eastman  positive  cinematograph  film,  sold  for  dental 
radiographic  purposes. 

8.  Time  of  exposure:     About  10  seconds. 

9.  Time  in  developer  and  developer  used:  About  8  minutes  in: 
Water,  10  oz. ;  sulphite  of  soda  (crystals),  4  oz. ;  carbonate  of  potash, 
3  oz. ;  adurol,  y2  oz.  From  the  concentrated  solution  take  2  oz.  to  6  oz. 
of  distilled  water,  and  to  this  mixture  add  15  drops  of  10%  solution  of 
potassium  bromide. 

To  make  the  negative  of  the  radiograph  shown 
fig.  i2it  in  Fig.  121  the  conditions  were  as  follows: 

1.  Machine  used:  A  Scheidel  12-inch  induction 
coil,  with  i-point.  electrolytic  interrupter,  operating  on  a  no-volt  D.  C. 
circuit.     All  of  the  resistance  of  rheostat  cut  out. 


Fig.    121.      By    (.".    Edmund    Kelts,   Jr.,    of    New   Orleans,    La. 


2.  Strength  of  current:  Thirty  (30)  amperes  in  primary.  Twelve 
(12)  inches  of  fat,  fuzzy  spark  obtainable. 

3.  Make  and  condition  of  tube :  "Cloverleaf "  6-inch  tube.  Length 
of  tube-regulating  spark  gap,  4  inches.  Tube  backs  up  10^2  inches  of 
parallel  spark. 

4.  Distance  of  target  from  film:     Eight  (8)  inches. 

5.  Thickness  of  part:   That  of  lower  jaw  and  overlying  parts. 

6.  Density  of  part:     That  of  lower  jaw  and  overlying  parts. 

7.  Film  used  :     Eastman's  positive  cinematograph  emulsion. 

8.  Time  of  exposure:     One  (1)  second. 

9.  Time  in  the  developer  and  developer  used:  (Time  not  given.) 
Developing  started  in  metol-hydroquinone  and  finished  in  hvdroquinone. 

Comment :  Notice  that  the  distance  between  the  target  and  the  film 
is  8  inches.  Therefore,  the  distance  between  the  glass  of  the  tube  and 
the  patient's  face  is  only  about  4  inches.  With  the  tube  this  close  a 
"filter"  (Chap.  VIII)  should  be  used  to  protect  the  patient.  An  alumi- 
num filter  was  used  in  this  case. 


CHAPTER  VI. 

Reading  Radiographs. 

Seeing  things  is  truly  a  mental  effort.  Though  an  object  or  shadow 
be  reflected  on  the  retina  of  the  eye,  it  is  not  "seen"  unless  it  has  an  effect 
upon  the  brain.  When  we  say,  "train  the  eye"  to  see  such  and  such  a 
thing,  we  mean  really,  train  the  mind — the  brain. 

To  correctly  read  a  radiograph,  to  see  all  there  is  in  it  to  be  seen, 
and  to  understand  it  to  mean  what  it  stands  for,  requires  experience  and 
an  intimate  knowledge  of  the  anatomy  and  pathology  of  the  parts  under 
observation.  Experience  is  an  important  factor.  Upon  looking  over  old 
negatives,  I  see  many  things  of  interest  in  them  now  which  I  did  not 
observe  a  year  ago. 

It  is  always  advisable  to  study  the  negative  in 

Illuminating  preference  to  the  print.     Some  of  the  finest  details 

BOXCS.  are  lost  in  the  print.     The  negative  may  be  held  up 

to  a  window  or  an  artificial  light,  or  it  may  be  placed 

in  an  illuminating  box  (Fig.  122)  for  observation. 

While  the  illuminating  boxes  on  the  market  are  suitable  for  studying 
large  plate  or  film  negatives,  they  are  needlessly  large  and  poorly  adapted 
for  studying  the  small,  dental,  film  negatives.  A  small  illuminating  box 
can  easily  be  made.  A  light-proof  box,  with  a  window  of  frosted  glass 
and  a  light  inside,  may  constitute  the  illuminating  box.  It  is  well  to  paint 
the  inside  of  the  box  white,  so  increasing  the  power  and  uniformity  of  il- 
lumination. With  the  negative  held  against  the  frosted  glass  of  the  window 
on  the  outside  and  the  light  lit  inside,  one  is  able  to  study  the  negative  to 
great  advantage.  Little  spring  steel  clips,  similar  to  the  ones  used  to  hold 
a  slide  or  a  microscope,  may  be  used  to  hold  the  negative  against  the 
frosted  glass   window. 

The  use  of  a  reading  glass  in  connection  with  an  illuminating  box 
will  enable  one  to  observe  the  negative  to  the  best  possible  advantage. 

The   denser    the    part,  the   deeper  will  be  the 

the  Relative  shadow  thrown  on  the  film,  and,  consequently,  the 

Ualues  of  Dense        more  transparent  the  negative  in  that  region.     Thus 

Areas  in  negatives,     in  the  negative,  metal  fillings,  posts  and  metal  crowns 

appear  as  transparent  areas ;    gutta-percha,  cement, 

136 


READING    RADIOGRAPHS 


*37 


enamel  and  porcelain  a  little  less  transparent ;  then  in  the  order  of  their 
respective  densities,  dentin,  bone,  gum  tissue,  and,  last,  the  cheek  appears 
— when  it  is  shown  in  the  negative  at  all — as  the  least  transparent  part, 
except  that  part  of  the  negative  on  which  the  X-Rays  have  fallen  directly 
without  anything  intervening  except  the  black  paper  of  the  packet.  The 
contrast  between  tooth  and  bone  tissue  is  very  marked.  Unfilled  canals 
and  pulp  chambers  appear  as  dark  streaks  and  areas  in  the  teeth.  Filled 
canals  and  pulp  chambers  appear  light.     Pulp  stones  appear  as  lighter 


Fig.     122.     An     Illuminating    Box. 


spots  in  the  dark  of  the  pulp  canal  or  chamber.  Abscess  cavities  appear 
as  dark  areas.  It  is  easy  to  distinguish  enamel  from  dentin,  and  the  peri- 
dental membrane  can  clearly  be  seen  as  a  dark  streak  following  the  out- 
line of  roots.  A  bit  of  calculus  in  the  peridental  membrane  will  appear 
as  a  light  spot.  This  calculus  must  be  on  either  the  mesial  or  distal  side 
of  a  root  to  be  seen.  It  could  not  be  radiographed  if  it  occurred  on  the 
buccal,  or  labial,  or  lingual. 

All  the  foregoing  may  be  seen  in  good  negatives, 
negatives    Prints        but  a^  tms  cann°t  be  seen  in  prints  and  half-tones. 
and  fjalf-tone  I  recall  distinctly  having  read  an  article  on  Dental 

Reproductions.  Radiography  in  which  the  writer  printed  a  half-tone 

and  told  his  readers  to  "observe  the  enamel,  the  den- 
tin and  the  peridental  membrane."    The  writer  of  this  article  wrote  his 


[38  DENTAL   RADIOGRAPHY 

paper  with  either  a  negative  or  a  good  print  before  him,  and  assumed 
that  all  he  saw  there  would  be  reproduced  in  the  half-tone.  It  was  not. 
The  half-tone  was  so  dark  that  all  detail  of  the  picture  was  lost,  and  the 
best  that  could  be  done  was  to  distinguish  between  bone  and  tooth  struc- 
ture. Let  us  stop  to  consider  the  steps  in  the  making  of  a  half-tone  pic- 
ture and  the  chance  for  the  loss  of  detail  is  apparent.  From  the  negative 
a  new  picture  is  made  on  photograph  paper,  the  print.  From  this  another 
picture  is  made  on  a  half-tone  plate,  and  from  this  the  half-tone  picture 
is  printed  on  paper  with  ink. 

The  finest  details  of  a  negative  cannot  be  shown  in  a  half-tone,  and, 
though  I  have  seen  many  prints  that  seemed  to  have  fully  as  much  detail 
as  the  negative,  there  is  usually  at  least  a  slight  loss  of  minute  detail  even 
in  well  made  prints. 

I  have  stated,  that  in  order  to  make  a  half-tone  picture  it  is  neces- 
sary first  to  make  a  photographic  print  or  picture  from  the  negative,  then, 
from  this,  to  make  the  half-tone  picture.  Thanks  to  the  efforts  of  Dr.  Ot- 
tolengui  and  his  co-workers,  I  am  able  to  print  half-tones  made  directly 
from  negatives.  The  difference  in  the  appearance  of  a  half-tone  made 
from  a  negative  and  one  made  from  a  photographic  print  is  shown  in 
Fig.  123  (made  directly  from  the  negative)  and  Fig.  124  (made  from 
the  photographic  print,  but  reversed  in  the  process  for  easier  comparison). 

Densities — deep  shadows — we  have  seen  appear 
Relative  Ualues  as  transparencies  in  the  negative.  The  print,  or  posi- 
Of  Shadows  in  tive,    is    the    opposite   of    the    negative.      Hence,    in 

Prints.  prints,  and  half-tones  made  from  them,  we  see  the 

deep  shadows  of  metal  fillings,  crowns  and  posts  ap- 
pearing very  dark,  gutta-percha,  cement,  enamel  and  porcelain  a  little 
less  dark,  and  so  on.  On  the  print,  filled  canals  appear  dark,  unfilled 
ones  light,  abscesses  appear  as  light  areas,  and  so  on,  always  the  opposite 
of  the  negative. 

In  order  to  avoid  confusion  of  the  right  and  left  sides  when  studying 
a  negative,  bear  the  following  in  mind  :  When  looking  at  the  negative 
from  its  film  side  it  is  as  though  you  observed  the  part  radiographed 
from  the  position  occupied  by  the  tube  during  the  exposure.  When  look- 
ing at  the  negative  with  the  film  side  presenting  towards  the  light,  away 
from  the  eye,  it  is  as  though  you  observed  the  part  from  the  position  of 
the  film  during  exposure.  This  is  the  case,  granting  that  the  sensitive 
side  of  the  film  presented  toward  the  object  radiographed  at  the  time  of 
exposure,  a  condition  that  should  always  obtain  excerjt  when  an  intensify- 
ing screen  is  used. 

If  the  techjiic  previously  given  is  followed,  and  the  sensitive  side  of 
the  film  or  plate  be  placed  so  as  to  present  toward  the  part  to  be  radio- 


1\I'..U  >1  .\  (,      K. -IUIULi  K.  II    I  I  $ 


139 


140 


/  >/;'.Y  TAL   RADIO  GRAPH ) ' 


READING  RADIOGRAPHS  141 

graphed,  and  then  the  negative  placed  in  the  printing  frame  with  the 
sensitive  side  up  (this  must  be  done,  or  there  will  be  a  loss  of  detail) 
when  observing  prints,  it  is  as  though  one  looked  at  the  part  from  the 
position  of  the  film  or  plate  during  exposure. 

When  observing  half-tones  made  from  photographic  prints  it  is  the 
same  as  when  observing  the  prints  themselves,  unless  special  steps  have 
been  taken  in  the  process  of  making  the  half-tones  to  reverse  the  sides, 
as  was  dmie  in  Fig.  124.  When  observing  half-tones  made  from  negn- 
tives  it  is  the  same  as  observing  negatives  from  the  film  side. 

When  looking  at  radiographs  made  directly  on  paper,  it  is  as  though 
you  observed  the  part  from  the  position  of  the  tube  during  exposure. 

How   to   mark   negatives   is   a   subject  that  has 

marking  caused  the  use  of  a  great  deal  of  perfectly  good  paper 

negatives.  and  ink.     After  trying  several  methods,  I  no  longer 

attempt  to   mark   my   negatives,   but  place   them   in 

envelopes  and  mark  the  envelopes  as  desired.     The  Lumiere  Dry  Plate 

Co.  print  the  following  outline  on  the  backs  of  their  envelopes : 

No 

Name 

Address    

Date    

Case    

Tube  used  

Exposure  

Distance  of  Tube  from  Plate .» 

Developer    

Referred   by    Doctor 

Remarks    

I  have  lately  heard  of  an  "X-Ray  ink"  for  marking  negatives,  but 
have  been  unable  to  procure  any.  The  desired  markings  are  placed  on 
the  envelopes  or  black  paper  covering  the  plate  or  film,  the  marking  being 
done  on  the  side  of  the  envelope  or  black  paper  presenting  toward  the 
sensitive  side  of  the  plate  or  film,  so  that  when  the  exposure  is  made  the 
ink  markings  are  between  the  source  of  the  rays  and  the  sensitive  side  of 
the  plate  or  film.  This  ink  must,  I  think,  contain  some  salt  of  lead  or 
bismuth,  for  the  X-Rays  penetrate  it  very  poorly,  and  consequently  there 
is  a  shadow  cast  on  the  negative. 

My  objections  to  marking  small  dental  films  in  this  manner  is  that 
occasionally  the  shadow  of  the  markings  will  occur  in  such  a  place  in  the 
radiograph  as  to  spoil  the  picture.  The  older  methods  of  placing  wires 
bent  to  form  the  figures  or  letters  for  marking,  or  a  stencil  of  sheet  metal, 
between  the  source  of  rays  and  the  plate,  is  highly  unsatisfactory,  so  far 
as  their  application  to  the  marking  of  small  dental  radiographs  is  con- 


142 


DEXTAL  RADIOGRAPHY 


cerned.  After  the  negative  is  made,  markings  may  be  scratched  in  the 
film.  But,  as  I  said  before,  no  system  of  marking  the  negative  itself  is 
as  satisfactory  as  marking  the  envelope  in  which  it  is  kept. 

One  of  the  most  unfortunate  limitations  of  the 

Perspective.  radiograph  is  that  it  lacks  perspective.     For  example, 

though  we  are  able  to  observe  the  exact  mesio-distal 


Fig.    125.       (Reduced    one-half.) 


position  of  an  impacted  tooth,  we  are  unable  to  determine  its  bucco-  or 
labio-lingual  position,  with  any  degree  of  accuracy. 

The  closer  the  object,  which  is  being  radiographed,  is  to  the  film 
during  exposure,  the  clearer  the  resulting  shadow  will  be.  Thus,  for 
example,  if  an  impacted  cuspid  lay  lingually  to  the  other  teeth,  and  the 
film  were  held  inside  the  mouth  as  usual,  the  detail  in  the  picture  of  the 
cuspid  would  be  a  little  greater  than  the  detail  in  the  other  teeth.  If  the 
cuspid  lay  to  the  labial, —  farther  away  from  the  film, — detail  in  it  would 
be  less  than  in  the  other  teeth.  Hut,  on  the  whole,  this  method  of  deter- 
mining bucco-  or  labio-lingual  location  i^  unreliable. 


RliADLXG  RADIOGRAPHS 


143 


While  I  agree  with  Dr.  C.  H.  Abbot,  of  Berlin,  who  has  done  some 
writing  and  experimental  work  to  prove  that  radiographs  are  not  totally 
lacking  in  perspective,  yet  I  do  declare,  from  the  standpoint  of  their  prac- 
tical application  to  dentistry,  that  they  are  simply  shadow  pictures.  And 
let  me  here  warn  you  that  like  all  shadows,  X-Ray  pictures  are  often  ex- 
tremely misleading;  one  might  say,  for  the  word  seems  to  fit  so  well, 
treacherous.  To  eliminate  the  chance  of  misreading,  because  of  distor- 
tion of  the  radiograph,  it  is  often  expedient  to  make  several  pictures  of 
the  same  part  or  field,  changing  the  pose.     Even  this,  however,  does  not 


Fig.    126.      A    dental    fluoroscope.        Fig.    127.      Shadows    of   teeth    cast    on    the    fluoroscope. 


preclude  the  possibility  of  misinterpretation.  To  correctly  read  radio- 
graphs, a  man  must  be,  not  only  a  student  of  radiography,  anatomy,  his- 
tology and  pathology,  but  he  must  have  and  use  that  gift  of  the  gods — 
common  sense.  He  must  not  jump  at  conclusions,  and  he  should  ever 
regard  the  radiograph  as  a  shadow  picture,  liable  to  all  the  apparent  mis- 
representations of  shadows. 

A  study  of  Fig.  125  will  convince  anyone  of  the  lack  of  perspec- 
tive in  at  least  some  radiographs.  One  is  unable  to  determine,  from 
observing  this  radiograph,  whether  the  coin  pictured  is  in  the  flesh  of 
the  hand,  on  the  back  of  the  hand,  or  in  the  palm  of  the  hand.  Likewise, 
from  simple  observation,  it  is  impossible  to  tell  whether  the  needle  is  in, 
on,  or  under  the  hand.  By  deduction,  we  may  come  to  this  conclusion : 
The  coin  was  nearer  the  plate,  during  its  exposure,  than  the  needle,  be- 
cause the  outline  of  the  coin  is  much  clearer  than  that  of  the  needle,  and 
other  things  remaining  equal,  the  closer  the  object  being  radiographed  is 
to  the  plate,  the  clearer  its  shadow  will  be.     Still  we  cannot  determine 


M4 


DENTAL   RADIOGRAPHY 


the  exact  location  of  either  needle  or  coin.  We  know  only  that  the  coin 
was  somewhat  closer  to  the  plate,  during  its  exposure,  than  the  needle. 
That  is  all. 

The  coin  lay  under  the  hand  on  the  envelope  holding  the  plate,  the 
needle  on  the  back  of  the  hand,  when  the  exposure  for  Fig.  125  was  made. 

To  overcome  the  fault  of  the  lack  of  perspective 
Stereoscopic  and.  to  some  extent,  the  distortion  in  radiographs, 

Radiography.  one  must  resort  to  stereoscopic  radiography. 

Stereoscope  radiography  is  the  science  and  art 
of  making  radiographs,  which,  when  observed  through  a  stereoscope,  have 
perspective.  The  technic  of  making  stereoscopic  radiographs,  together 
with  a  discussion  of  their  value  and  efficiency,  will  be  dealt  with  at  some 
length  in  a  subsequent  chapter. 

A  work  of  this  kind  would  be  incomplete  with- 
Dental  out   some  mention  of   the   dental  fluoroscope.     The 

fluoroscope.  simplest   and   most   efficient   dental   fluoroscope   has 

been  designed  by  Dr.  Tousey  (Fig.  126).  Like 
all  fluoroscopes,  this  one  depends  on  calcium  tungstate,  or  platino-barium 
cyanide,  for  its  action.  A  disc  of  cardboard,  coated  on  both  sides  with 
either  of  the  above  named  chemicals,  is  placed  between  two  discs  of 
transparent  glass,  and  the  glasses  and  cardboard  (or  fluorescent  screen, 
for  the  cardboard  becomes  a  fluorescent  screen  when  it  is  coated  with 
calcium  tungstate  or  platino-barium  cyanide)  held  together  by  means  of 
a  circular  band  of  metal.  A  handle  now,  and  we  have  a  dental  fluoro- 
scope, the  screen  protected  against  moisture,  and  either  side  of  it  may 
be  used. 

To  use  the  fluoroscope,  the  operating  room  should  be  dark.  It  is 
best  that  the  operator  remain  in  this  darkened  room  for  some  time  until 
his  eyes  become  accustomed  to  the  darkness  before  making  the  exposure. 
Hold  the  fluoroscope  inside  of  the  mouth,  and  have  the  tube  placed  so 
that  the  X-ravs  will  pass  through  the  part  to  be  observed,  and  strike  the 
fluoroscope.  Fig.  127  shows  the  fluoroscope  and  a  shadow  of  the  teeth 
thrown  on  it. 

The  disadvantages  of  the  fluoroscope  are: 
r.     The  operator  must  expose  himself  to  the  actions  of  the  X-rays. 

2.  Either  the  time  for  observation  must  he  made  very  short,  or  both 
operator  and  patient  must  he  exposed  to  the  rays  unnecessarily  and 
dangerously  long. 

3.  The  picture  on  the  fluoroscope  lacks  detail. 

4.  Xo  record  of  the  case,  other  than  a  mental  picture,  can  he  kept; 


READING  RADIOGRAPHS  145 

while  a  negative  may  he  referred  to  as  often  as  expediency  or  neces- 
sity demands. 
5.      From  an  educational  standpoint,  the  fact  that  prints,  lantern  slides 
and  half-tones  can  be  made  from  negatives  is  a  great  advantage. 
To  learn  to  eat  olives,  one  must  eat  them,  so  I  am  told.     To  learn 
to  read  radiographs,  one  must  read  them,  and  so  we  pass  to  the  next 
chapter,  wherein  we  shall  study,  in  a  practical  way,  the  reading  of  radio- 
graphs. 


CHAPTER  VII. 

the  Uses  of  the  Radiograph  in  Dentistry. 

The  use  of  the  radiograph  in  the  practice  of  modern  dentistry  is 
almost  limitless.  Some  of  the  cases  hereinafter  mentioned  are  such  as 
the  general  practitioner  of  dentistry  might  not  be  called  upon  to  diagnose 
or  treat  oftener  than  once  or  twice  in  a  lifetime,  if  at  all.  But  by  far 
the  greater  number  of  them  are  such  as  are  met  repeatedly  in  the  prac- 
tice of  dentistry. 

The  radiograph  may  be  used  in  the  following  cases:  (i)  In  cases 
of  delayed  eruption,  to  determine  the  presence  or  absence  of  the  un- 
erupted  teeth.  (2)  In  cases  where  deciduous  teeth  are  retained  long 
alter  the  time  when  they  should  have  been  shed,  to  learn  if  the  succe- 
daneous  teeth  be  present.  (3)  To  learn  if  the  roots  of  children's  teeth 
be  fully  formed.  (4)  To  determine  whether  a  tooth  be  one  of  the  pri- 
mary or  secondary  set.  (5)  To  determine  when  to  extract  temporary 
teeth.  (6)  To  show  the  orthodontist  when  he  may  move  the  coming 
permanent  teeth  by  moving  the  deciduous  teeth.  (7)  To  observe  moving 
teeth.  18)  In  cases  of  supernumerary  teeth.  (9)  In  cases  of  impacted 
teeth  as  an  aid  in  extraction.  (10)  To  determine  the  number  of  canals 
in  some  teeth.  (11)  As  an  aid  in  filling  the  canals  of  teeth  with  large 
apical  foramina.  (12)  To  learn  if  canals  are  open  and  enlarged  to  the 
apex  before  filling  and  to  observe  the  canal  filling  after  the  operation. 
(13)  To  determine  whether  an  opening  leading  from  a  pulp  chamber 
be  a  canal  or  a  perforation.  (14)  In  cases  of  pulp  stones  (nodules). 
(15)  In  cases  of  secondary  dentine  being  deposited  and  pinching  the 
pulp.  V16)  To  learn  if  the  filling  in  the  crown  encroaches  on  the  pulp. 
(17)  In  cases  of  teeth  with  large  metal  fillings  or  shell  crowns  which 
do  not  re-pond  to  the  cold  test,  to  learn  if  the  canals  are  filled.  (18) 
To  learn  if  apical  sensitiveness  is  due  to  a  large  apical  foramen  or  an 
unremoved,  undevitalized  remnant  of  pulp.  (19*)  In  cases  of  chronic 
pericementitis  ("lame  tooth").  (20)  In  cases  of  alveolar  abscess  to  de- 
termine which  tooth  is  responsible  for  the  abscess.  (21  )i  In  cases  of 
alveolar  abscess  to  determine  the  extent  of  the  destruction  of  tissue — 
bony  and  tooth.  (22)  In  cases  of  alveolar  abscess  to  learn  how  many 
teeth  are  involved.  (23)  In  cases  of  abscess  of  multi-rooted  teeth  to 
learn  at  the  apex  of  which  root  the  abscess  exists.     (24)    In  cases  of 

146 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     147 

abscesses  of  crowned  teeth  to  learn  whether  the  canals  are  properly  filled. 
(  2^')  As  an  aid  in  differential  diagnosis  between  chronic  alveolar  abscess 
and  pyorrhea  alveolaris.  (26)  To  observe  destruction  of  tissue , due  to 
pyorrhea  alveolaris.  (2J)  In  cases  of  pericemental  abscess.  (28)  In 
cases  of  persistent  suppuration  which  does  not  yield  to  the  usual  treat- 
ment. (In  fact  in  all  cases  that  do  not  yield  promptly  to  the  usual 
course  of  treatment.)     (29)    To  observe  the  course  of  a  fistulous  tract. 

(30)  To  observe  the  field  of  operation  before  and  after  apicoectomy. 

(31)  To  locate  foreign  bodies,  such  as  a  broach  in  the  pulp  canal  or 
tissues  at  the  apex  of  a  tooth ;  a  piece  of  wooden  toothpick  in  the  peri- 
dental membrane,  etc.  (32)  To  determine  the  presence  or  absence  of 
a  bit  of  root  imbedded  in  the  gum  tissue.  (33)\  To  diagnose  fracture 
of  a  root.  (34)  To  observe  the  size  and  shape  of  the  roots  of  teeth  to 
be  used  in  crown  and  bridge  work.  (35)  As  an  aid  and  safeguard  when 
enlarging  canals  for  posts.  (36)  To  examine  bridges  about  which  there 
is  an  inflammation.  (37)  To  observe  the  field  before  constructing  a 
bridge.  (38)  To  observe  planted  teeth.  (39)  In  cases  of  cementoma. 
(40)  In  cases  of  bone  "whorls."  (41)  To  locate  stones  (calculi)  in  the 
salivary  ducts  or  glands.  (42)  In  cases  of  bone  cysts.  (43)  In  cases 
of  dentigerous  cysts.  (44)  In  cases  of  tumor,  benign  or  malignant.  (45) 
To  observe  anomalous  conditions,  such  as  the  fusion  of  the  roots  of  two 
teeth  for  example.  (46)  To  observe  the  location  and  extent  of  a  necrotic 
or  carious  condition  of  bone.  (47)  To  diagnose  antral  empyema.  (48) 
To  observe  size,  shape  and  location  of  the  antrum  as  an  aid  in  opening 
into  it.  (49)  To  locate  foreign  bodies,  such  as  tooth  roots  or  broaches, 
in  the  antrum.  (50)  To  observe  cases  of  luxation.  (51)  In  cases  of 
fracture  of  the  jaw  before  and  after  reduction.  (52)  In  cases  of  anky- 
losis of  the  temporo-mandibular  articulation  or  the  joint  formed  by  the 
tooth  in  the  jaw.  (53)  To  observe  the  field  of  operation  before  and  after 
resection  of  the  mandible.  (54)  In  all  cases  of  facial  neuralgia  with 
an  obscure  etiology.  (55)  To  observe  the  inferior  dental  canal.  (56)  In 
cases  of  Ludwig's  angina.  (57)  In  cases  of  insomnia,  neurasthenia, 
insanity*  and  kindred  nervous  disorders.  (58):-  In  cases  of  periodic 
headaches.  (59  V1  In  cases  of  facial  gesticulatory  tic  (spasmodic  twitch- 
ing of  a  set  of  the  facial  muscles).  (60)  To  allay  the  fears  of  a 
hypochondriac.  (61)  In  cases  where  the  patient  cannot  open  the  mouth 
wide  enough  for  an  ocular  examination.  (62)  In  research  work  to 
study  osteology,  the  development  of  teeth,  action  of  bismuth  paste,  bone 
production  and  destruction,  changes  occurring  in  the  temporo-mandibular 
articulation  when  jumping  the  bite,  blood  supply  to  parts,  resorption  of 


*Dr.   Upson — Cleveland. 


i48  DENTAL   RADIOGRAPHY 


teeth  and  the  causes  for  it,  etc.  (63)  As  a  record  of  work  done.  (64)  In 
cases  of  hidden  dental  caries. 

It  is  with  a  mingled  feeling  of  enthusiasm  and  misgiving  that  I 
now  attempt  to  illustrate  the  above  named  uses  of  the  radiograph.  It 
is  not  reasonable  to  hope  that  half-tones  will  show  all  that  can  be  seen 
in  negatives.  As  a  result,  things  may  be  mentioned  in  the  text  that 
cannot  be  observed  in  the  half-tones ;  but,  be  assured,  all  clinical  factors 
mentioned   in  the  text  were  observable  in  the  original   radiographs. 

Thanks  to  the  help  rendered  by  the  many  radiographers,  whose 
names  appear  beneath  the  half-tones,  and  the  practitioners,  whose  names 
are  mentioned  in  the  text.  I  will  be  able  to  illustrate  almost  all  of  the 
above  enumerated  uses.  I  have  tried  to  make  this  collection  of  radio- 
graphs representative — that  is,  to  have  it  represent  the  work  of  Ameri- 
cans in  the  field  of  dental  radiography. 

In  describing  cases  which  have  not  come  under  direct  personal  ob- 
servation there  is,  of  course,  considerable  liability  to  mistakes.  I  ask 
my  readers  to  bear  this  in  mind. 

It  shall  be  my  policy  to  print  as  few  radiographs  as  possible  to  fully 
demonstrate  the  different  uses.  For  example,  I  could  print  hundreds 
of  different  radiographs  illustrating  the  use  "in  cases  of  delayed  eruption 
to  determine  the  presence  or  absence  of  the  unerupted  teeth."  But  only 
a  few  will  be  used,  because  that  is  all  that  is  necessary  to  demonstrate 
the  value  of  the  radiograph  in  such  cases,  and  to  use  more  would  be 
superfluous  in  a  work  of  this  kind. 

1.    In  Gases  of  Delayed   eruption  to  Determine  the  Presence  or  Absence  of  the 

Unerupted  teeth. 

Upper,  permanent  laterals  missing  in  the  mouth 

Tig.  128.  of  a  girl,  eighteen  years  of  age.    Spaces  between  the 

centrals,  and  the  centrals  and  cuspids.     In  this  case 

the  deformity  seemed  particularly  distressing  because,  save  for  the  spaces 

between  her  teeth,  the  young  lady  was  positively  beautiful. 

A  radiograph  (Fig.  128)  was  made  and  shows  that  the  laterals  are 
not  impacted  in  the  upper  maxilla.  It  therefore  became  necessary  to 
move  the  centrak  together  and  construct  a  bridge.  Had  the  laterals 
been  present  in  the  maxilla,  and  space  made  for  them  by  moving  the 
centrals  together,  they  would  probably  have  erupted  into  their  places. 
Had  they  not  erupted  after  space  had  been  made  for  them  the  tissues 
covering  them  could  have  been  dissected  away,  holes  drilled  into  the 
teeth,  little  hooks  cemented  into  these  holes  and  the  teeth  elevated  or- 
thodontically. 


THE  USES  OF   THE  RADIOGRAPH  IN  DENTISTRY     149 

When  there  seems  to  be  a  congenital  absence  of 
fig.    129.  a  tooth  from  the  jaw  it  is  expedient — which  is  ex- 

pressing it  mildly — to    use    the    radiograph    before 
constructing  and  setting  a  bridge.   Failure  to  do  this  might  result  in  what 


Fig.   128.      Congenital   absence  of  the   upper   lateral   incisors.      Age   of  patient,   eighteen   years- 


Fig.  129.  Fig.  130. 

Fig.  129.     Bridge  from  central  to  first  bicuspid.     Unerupted  cuspid.     The  arrow  points  to  a  bit 

of   tooth   root.      (Radiograph   by   Ream   of   Chicago.) 

Fig.  130.     An  upper  cuspid  in  the  place  of  the  lateral.     A  temporary  cuspid  in  the  place   which 

should  be  occupied  by  permanent  cuspid.     The  lateral  missing   from  the   jaw. 

is  shown  in  Fig.  129 — an  unerupted  cuspid  covered  with  a  bridge.  Such 
a  condition  as  this  may  or  may  not  cause  local  inflammation,  neuralgia, 
or  any  of  a  series  of  inflammatory  and  nerve  disorders.  In  this  case  the 
bridge  covers  not  only  an  unerupted  cuspid,  but  also  a  bit  of  tooth  root. 

In  a  case  presented  to  me  an  upper  permanent 

fig.    130.  cuspid  was  seen  occupying  the  place  of  the  lateral 

incisor,   and   a   temporary   cuspid   was   in  the   space 


I^O 


DEXTAL   RADIOGRAPHY 


Fig.   131. 


Fig.  132. 


Fig.    131.     Congenital   absence   of   the   upper   second   bicuspid.      Observe    the    orthodontia   appliance 

in    position.      (Radiograph    by    Lewis    of    Chicago.) 
Fig.    132.      Delayed  eruption  of  an  upper  second  bicuspid.     The   orthodontia  appliance  in  position 
is  being  used  to  make  space  in  the  arch  for  the  delayed  tooth.   (Radiograph  by  Lewis  of  Chicago.) 


\  bad! 


impacted  '  d  bicuspid,  with  no  span-  aj  .'ill  for  it  in  the  dental  arch. 

(Radiograph   by   Pancoast   of   Philadelphia.) 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     151 

which  should  have  been  occupied  by  the  permanent  cuspid.  A  radio- 
graph was  made  1  Fig.  130)  to  locate  the  missing  lateral.  It  was  not 
present  in  the  jaw.  Though  I  am  not  absolutely  sure  of  this,  I  never- 
theless feel  quite  certain  that  the  permanent  lateral  was  mistaken  for  a 


Fig.    A. 
Odontoma   in   patient   eight   years    old.      (Radiograph    by    Schamberg,    of   New    York.) 


temporary  tooth  and  extracted  when  the  patient  was  about  seven  or 
eight  years  old — a  mistake  which  could  not  have  happened  had  the  dentist 
used  radiographs. 

Fig.   131  proves  the  absence  of  a  second  bicus- 

Tigs.  131  and  132.        pid  and  shows  that  bridgework  must  be  resorted  to, 

to   fill   the   space.     Fig.    132   discloses   the  presence 

of  a  second  bicuspid  and  shows  that  it  will  not  be  necessary  to  make  a 

bridge.     As  they  appeared  before  radiographs  were  taken  the  cases,  from 

which  Figs.  131  and  132  were  made,  were  similar. 


Fig.     133,    a    case    of    Dr.    Oyer's,    shows    a 
Tig.    133.  badly  impacted  lower  second  bicuspid  with  no  space 

at  all  for  it  in  the  dental  arch. 


i ;_' 


DENTAL   RADIOGRAPHY 


With  the  exception  of  the  third  molars  no  teeth 

fig,  i34,  are  so  liable  to  be  delayed  in  their  eruption  as  the 

upper    cuspids.      For   this    reason,    when    making   a 

radiograph  to  determine  the  presence  or  absence  of  an  unerupted  cuspid 


Fig.    b. 
Same    patient.    n]<\  .,-ii.     side    of   jaw.      ( Radiograph    1  >y    Sclianiberg,    of    New    York.) 


or  a  third  molar,  1  feel  tolerably  sure,  before  I  make  the  picture,  that 
the  tooth  will  be  found  somewhere  in  the  jaw.  When  the  missing  tooth 
is  a  central,  lateral,  bicuspid,  or  lower  cuspid,  I  am  in  doubt  as  to 
what  to  expect.  My  experience  teaches  me  that  when  these  teeth  are 
missing  they  are  just  as  likely  to  be  entirely  absent  from  the  jaw  as 
present  in  it.  and  simply  unerupted.  So  far,  I  have  never  seen  either 
long  delayed  eruption  or  congenital  absence  of  the  first  <>r  second  molars. 
Since  the  tir-t  publication  of  the  above.  Dr.  Ottolengui  has  reported 
two  interesting  cases  (Items  of  Interest,  February  [9,  [913),  from 
which  record   I  quote  in  part,  as   follows: 


THE   US  US  OF  THE  RADIOGRAPH  IN  DENTISTRY     [53 

"Very  shortly  after  Dr.  Raper  had  published  the 
missing  quoted   statement,  that  up  to  that   time  he  had   not 

first  molar.  seen  a  case  wherein  first  or  second  molars  were  con- 

genially absent,  a  little  girl  patient  of  mine  came  in 
for  her  periodical  examination,  and  I  noted  that  since  her  previous  visit 


Fig.    c. 

Patient    aged    13.      Right    side.      Two    upper    and    one    lower    molar    absent. 
Geo.   M.    McKee,   of   New   York.) 


(Radiograph    by 


she  had  erupted  three  first  permanent  molars,  but  the  fourth  had  not 
appeared.  I  immediately  began  to  wonder  whether  or  not  1  was  about  to 
discover  an  authentic  case  of  congenital  absence  of  a  first  molar.  I  say 
authentic,  because  in  records  of  this  kind  it  is  not  always  that  one  may 
be  sure  that  the  history  is  authentic.  But  in  this  particular  case  there 
can  be  no  doubt.  The  child  was  the  sister  of  another  girl  in  my  care  and 
had  been  under  my  observation  since  she  was  four  years  of  age.  I  have 
casts  of  her  mouth  at  the  age  of  five,  which  show  the  primary  denture 
complete.  I  may  add  also  that  there  never  had  nor  has  been  any  caries, 
and  consequently  there  was  no  possibility  that  a  molar  had  been  extracted, 
a  suspicion  always  warranted  when  we  find  a  first  molar  absent  from  the 


154 


DEXTAL  KADlOCR.ll'IIY 


mouth  of  an  adult.  An  ordinary  small  mouth  radiograph  was  made,  and 
while  it  did  not  disclose  the  shadow  of  a  molar,  neither  did  it  satisfac- 
torily show  what  really  existed.  I  therefore  determined  to  have  a  large 
radiograph  made,  so  that  we  might  have  a  picture  of  the  entire  bone. 


Fig.    D. 
atient.      Left    side.      Same    molars    absent.      (Radiograph    by    McKce,    of    New    York.) 


"The  patient  was  sent  to  Dr.  M.  I.  Schamberg.  who  made  radiographs 
of  both  sides  of  the  mandible,  that  we  might  compare  them.  The  radio- 
giaphs  are  reproduced  in  bigs.  A  and  15.  My  surprise  may  be  imagined 
when  I  found  that  in  the  region  which  should  have  been  occupied  by 
the  second  bicuspid  and  the  first  molar,  there  was  a  well-defined  com- 
posite odontoma.  And  perhaps  even  more  astonishing  is  the  position 
of  the  molar  lying  distally  of  the  tumor.  Whether  this  tooth,  which  is 
seen  lying  horizontally  in  the  bone,  is  the  first  molar  or  the  second  molar, 
is  a  question  that  has  been  raised  by  an  orthodontist  of  national  reputa- 
tion, a  man  of  keen  judgmenl  and  well  informed  as  to  tooth  forms.  While 
1  am  willing  to  admit  that  this  looks  more  like  a  first  than  a  second 
molar  ially  when  we  compare  with  the  normal  side  (Fig-  B),  still 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     155 

I  very  much  doubt  that  it  is  the  first  molar.  The  odontoma  is  more  apt 
to  be  a  composite  of  the  bicuspid  and  first  molar.  But  in  any  event, 
interesting  as  this  case  is.  it  cannot  be  entered  in  the  literature  as  a  record 
of  congenital  absence  of  a  first  permanent  molar,  because  that  tooth  is 
either  in  the  bone  or  else  is  included  in  the  odontoma,  whereas  by  "con- 
genital absence"  I  understand  to  be  meant  complete  non-existence. 

"The  second  case  which  I  am  permitted  to  report 
Itlissing  is  from  the  practice  of  Dr.  Thaddeus  P.  Hyat,  and 

Second  molars,  is  in  the  hands  also  of  Dr.  George  B.  Palmer 
for  orthodontic  treatment.  The  patient  is  a  boy  of 
fourteen,  and  we  are  assured  that  no  permanent  teeth  have  been  ex- 
tracted, yet  no  less  than  thirteen  permanent  teeth  are  missing.  In  the 
upper  jaw  the  absent  teeth  are:  both  lateral  incisors,  three  bicuspids, 
both  second  molars  and  both  third  molars,  a  total  of  nine  teeth  (note 
that  both  upper  laterals  are  absent,  while  both  upper  cuspids  are  pres- 
ent). In  the  lower  jaw  the  following  teeth  are  absent:  the  first  bicuspid 
and  the  third  molar  on  the  right  side  and  the  second  bicuspid  and  the 
third  molar  on  the  left  side. 

"Figs.  C  and  D  are  radiographs  of  the  two  sides  of  the  head.  In  the 
upper  the  first  molars  are  easily  distinguished,  but  there  are  no  evidences 
of  the  second  and  third  molars.  In  the  mandible  the  third  molars  are 
absent,  but  the  other  four  molars  are  present,  though  in  one  case  the 
crown  has  been  lost  by  caries.  Considering  4he  boy's  age,  this  seems  to 
be  an  authentic  record  of  congenital  absence  of  two  second  upper  molars, 
and  of  all  four  third  molars,  as  the  extraction  of  any  of  these  teeth 
could  not  have  been  forgotten. 

"Dr.  Hyat  has  kindly  asked  another  patient  of 

missing  first  ms  to  ca^  a*  my  °^ce  tnat:  I  might  examine  a  very 

Second  and  similar  case.    In  this  instance  the  patient  is  a  woman 

third  molars.  about    thirty-five    years    of    age.     She    is    a    highly 

cultured  person  engaged  in  the  editorial  department 

of  one  of  our  leading  magazines.     She  is  quite  positive  that  the  only 

tooth  she  ever  had  extracted  was  one  lower  first  molar.     If  this  be  true 

she  has  fourteen  teeth  congenitally  absent  as  follows  :     In  the  upper  jaw 

the  missing  teeth  are  the  two  lateral  incisors,  the  first,  second  and  third 

molars  on  the  left  side,  and  the  second  and  third  molars  on  the  right 

side.     In  the  lower  jaw  the  missing  teeth  are  the  second  bicuspid  and  all 

three  molars  on  the  right  side,  and  both  bicuspids  and  the  third  molar 

on  the  left  side.     Again  we  have  the  upper  laterals  missing,  and  the 

upper  cuspids  present. 


r56  DENTAL  RADIOGRAPHY 

"In  this  mouth  we  have  the  strange  anomaly  of  three  molars  missing 
from  the  upper  jaw  on  the  right  side,  and  three  molars  missing  from 
the  lower  jaw  on  the  left  side.  Enumerated  in  full  the  absent  molars 
were  all  four  of  the  third  molars,  three  of  the  second  molars  and  two 
of  tlu*  first  molars." 

Fig.  134  is  representative  of  a  class  of  delayed  eruption  that  is 
most  common.  I  could  print  as  many  as  forty  or  more  radiographs  of 
such  cases.     Fig.   123  was  a  beautiful  example.    The  age  of  the  patient 


Fig     134.      Age   of    patient,    fourteen.      An    unerupted    malposed    cuspid.      No    room    for    it    in    the 

dental   arch.      Obser\e    the   tipping   of   the    lateral,    which    is   probably   due   to   the   pressure    of   the 

cuspid  against  the  apex  of  its  root. 


in  this  particular  case  (Fig.  134)  was  some  months  over  fourteen.  The 
radiograph  was  made  for  an  orthodontist  who  was  just  beginning  treat- 
ment of  the  case.  There  was  no  evidence  of  the  presence  of  the  cuspid 
and  no  room  for  it  to  erupt.  When  the  arch  was  broadened  and  space 
made  for  it  the  cuspid  erupted.  It  required  some  mechanical  guidance 
to  make  it  come  into  its  exactly  proper  position. 

The  mere  making  of  space  for  them  in  the  arch  will  usually  result 
in  the  eruption  of  unerupted  teeth,  unless  they  are  badly  malposed.  If, 
after  space  is  made,  the  tooth  does  not  move,  the  gum  and  process  over 
it  should  be  slit  surgically.  If  this  does  not  suffice  to  induce  eruption, 
the  soft  parts  and  process  must  be  cut  away,  and  sometimes  it  may  be 
necessary  to  resort  to  the  use  of  orthodontia  appliances  to  assist  erup- 
tion, as   formerly   suggested. 


THE  USES  OE  THE  RADIOGRAPH  IN  DENTISTRY     157 

2.    Tn  Cases  Where   Deciduous  teeth  are  Retained  Cong  After  the  time  When 

they  Should  fiave  Been  Shed,  to  Cearn  if  the  Succedaneous 

teeth  be  Present. 

Case — Girl,    age     seventeen,     large     cavity     in 

fig.  135.  upper,  second,  deciduous  molar.    Whether  to  fill  this 

tooth  or  extract  it  depended  on  whether  there  was 

a  second  bicuspid  to  take  its  place  in  case  of  extraction.     It  was  not  at 

all  loosened  and  there  was  no  visible  evidence  of  the  presence  of  the  suc- 


Fig.  135.  Fig.   136. 

Fig.  135.     Age  of  patient,  seventeen.      Retained  upper,   second,  temporary  molar.     The  radiograph 

shows  that  the  second  bicuspid  is  present  in  the  jaw. 

Fig.    136.      Age   of   patient,    twenty-one.      Retained   lower,    second,    temporary    molar    with    a    large 

cavity    in    the   crown    of   the    tooth    and    the   roots    almost    entirely    resorbed,    despite    the    fact    that 

there  is  no   oncoming  second   rTicuspid. 


ceeding  bicuspid.  Fig.  135,  however,  shows  the  bicuspid  to  be  present. 
The  half-tone  may  not  do  so,  but  the  negative  now  before  me  has  per- 
spective enough  for  me  to  see  that  the  bicuspid  is  being  deflected  toward 
the  lingual.  The  deciduous  tooth  was  extracted  and  the  bicuspid  erupted 
promptly. 

Case — young  man,  age  twenty-one,  lower,  sec- 
Tig.  136.  ond,  deciduous  molar  with  pulp  exposed.  Question  : 
Should  the  tooth  be  treated,  filled  and  retained  in 
the  mouth,  or  extracted  to  make  room  for  the  second  bicuspid?  Fig. 
136  demonstrates  the  futility  of  attempting  to  treat  the  tooth — its  roots 
are  almost  entirely  resorbed  despite  the  fact  that  there  is  no  succedaneous 
tooth  in  the  jaw — and  shows  also  that  there  is  no  bicuspid  to  take  its 
place.     Extraction  and  bridgework  are  indicated. 

Fig.    137    shows    two    retained    temporary    up- 
Tifl.  137.  Per  cuspids  with  the  permanent  cuspids  impacted  and 

malposed. 


158 


DENTAL  RADIOGRAPHY 


Fig.    138   shows    two    retained,    primary,    lower 
Tig.    13$.  central  incisors  with  no  sign  of  the  permanent  cen- 

trals.    Age  of  patient,  seventeen. 

Case — a  young  man,  age  twenty-two;    with    a 
Tigs.  139  and  140.       retained,  temporary,  lower,  second  molar.     The  tem- 
porary tooth  was  too  short  to  reach  its  antagonists 
in  occlusion.     For  this  reason  the  patient,  a  dental  student,   wished  to 
have  it  crowned.    Before  making  the  crown,  a  radiograph  was  taken  (Fig. 


Fig.  137.  Fig.  138. 

Fig.   187.      Two   retained   temporary  cuspids,   with   the  permanent  cuspids   impacted   and   malposed. 

(Radiograph  by  Lewis,  of  Chicago.) 

Fig.    138.      Two    retained    temporary,    lower,    central  incisors.       No    permanent    centrals    present. 

Age   of   patient,    seventeen.      (Radiograph  by    Blum,    of    New    York    City.) 


[39)  after  the  development  of  which  it  was  seen  that  the  making  of  a 
crown  was  not  indicated.  From  the  appearance  of  the  radiograph  one 
might  suppose  that  the  temporary  tooth  was  loose — its  roots  being  almost 
entirely  resorbed.     But  such  was  not  the  case. 

Fig,  140  is  a  radiograph  of  the  same  case  one  month  after  the 
extraction  of  the  temporary  molar.  Notice  how  rapidly  the  bicuspid  is 
erupting  into  its  place.  The  force  of  eruption,  which  had  been  held  in 
abeyance  for  about  eleven  years,  became  promptly  active  upon  removal 
of  the  abating  object. 

Case — young  man,  age  twenty-one.    A  retained, 
Tigs.  141  and  142.       temporary,  upper  cuspid  with  no  observable  sign  of 
the   sun  cdancous   cuspid.     A   radiograph   was  made 
(Fig.  141  ),  but,  being  a  poor  one,  it  failed  to  show  the  looked-for  tooth. 
Yet  from  the  reading  of  this  radiograph  I  was  able  to  state  with  a  mod- 
erate degree  of  certainty  that  the  cuspid  was  present  in  the  jaw.    If  the 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     159 

tooth  itself  cannot  be  seen,  what  is  there  in  the  picture  to  lead  one  to 
believe  that  the  permanent  cuspid  is  present?  The  arrow  points  to  the 
upper  end  of  a  dark  line.  The  dark  line  represents  dense  bone  and  such 
a  line  almost  always  is  to  be  noted  in  radiographs  of  impacted  teeth. 


Fig.  139.  Fig.  140. 

Fig.  139.  Retained  temporary,  lower,  second  molar,  with  the  succedaneous  tooth  beneath  it.  Age 
of  patient,  twenty-two.  The  dark  spots  in  the  temporary  tooth  and  two  permanent  molars  are 
metal  fillings.  All  of  the  mesial  root  and  some  of  the  distal  root  of  the  temporary  tooth  resorbed. 
Fig.  140.  The  same  as  Fig.  139  one  month  after  extraction  of  the  temporary  tooth.  Observe 
how  rapidly  the  bicuspid  is  erupting.     When  this  picture  was  made  it  could  be  seen  in  the  mouth. 


Fig.   141.  

Fig.   142. 

Fig.  141.     Age  of  patient,  twenty-one.     A  retained  temporary  upper  cuspid.     The  arrow  points  to 
a   dark   line   following  along  the   side   of   the   impacted   cuspid.      The    impacted   tooth    itself  cannot 

be   seen. 
Fig.  142.     The  same  as  Fig.  141,  but  taken  at  a  different  angle  and  showing  the  permanent  cuspid. 

To  verify  or  disprove  my  deductions  another  radiograph  was  made 
(Fig.   142),  which  shows  the  impacted  cuspid  clearly. 

The  question  arises  naturally.  What  operative  procedure  should  be 


160  DENTAL   RADIOGRAPHY 

resorted  to  in  such  cases  as  the  one  just  described?  Had  the  patient 
been  younger,  or  had  the  root  of  the  temporary  cuspid  been  much  resorbed, 
or  had  the  pressure  of  the  impacted  tooth  been  causing  resorption  of 
the  permanent  lateral  root,  or  central  root,  or  had  the  patient  been  suf- 
fering from  neuralgia,  periodic  headaches,  or  any  nervous  disorder — 
had  any  of  these  conditions  existed  the  temporary  tooth  should  have  been 
extracted  immediately,  space  made  in  the  arch  for  the  permanent  tooth 
and  such  orthodontic  assistance  given  as  might  prove  necessary  to  cause 
it   (the  permanent  cuspid)   to  erupt  into  its  proper  place.     As  none  of 


Fig    143.     The  roots  of  a  lower,  first,  permanent  molar   not  quite   fully   funned.      Age  of  patient, 
eight   years   and   four  months.      Only   the  crowns   of   the  second   bicuspid   and   second   molar   are 

formed. 


these  conditions  did  exist,  and  as  the  patient  expressed  a  definite  disin- 
clination to  have  anything  done  unless  absolutely  and  imperatively  neces- 
sary, the  case  was  dismissed  with  the  understanding  that  the  condition 
should  be  kept  under  rigid  observation.  The  man  may  go  through  life 
without  trouble,  or  inside  of  a  year  he  may  be  suffering  almost  any 
nervous  disorder  from  simple  neuralgia  to  insanity* ;  or  he  may  lose 
the  temporary  cuspid  as  a  result  of  the  resorption  of  its  roots,  or  he 
may  even  lose  the  lateral  or  central  as  a  result  of  absorption  of  their 
roots,  or  suppuration  may  occur. 

3.    Co  Cearn  if  the  Roots  of  Children's  Ceetb  arc  fully  formed. 

Case — patient,  eight  years  and  four  months  old. 
Til.  143.  A   large  "cavity   in   a   lower   first,   permanent   molar. 

To  remove  absolutely  all  of  the  decalcified  dentin 
meant  extensive  exposure  of  the  pulp,  and,  therefore,  pulp  devitaliza- 
tion, extirpation  and  canal  filling.  But  should  we  practice  pulp  devitali- 
zation in  such  a  case?     If  the  roots  of  the  tooth  are  fully  formed,  yes; 

•Dr.   Upson 


THE  USES  OF   THE  RADIOGRAPH  IN  DENTISTRY     161 

if  the  roots  are  not  fully  formed,  no.  A  radiograph  (Fig.  143)  was 
made  and  shows  that  the  roots  of  the  tooth  are  not  quite  fully  formed. 
Accordingly  exposure  of  the  pulp  was  avoided,  the  unremoved,  decalcified 
dentin  painted  with  silver  nitrate,  a  paste  of  zinc  oxide  and  oil  of  cloves 
placed  in  the  bottom  of  the  cavity  and  the  tooth  filled  with  cement,  the 
object  of  this  treatment  being  to  conserve  the  pulp  in  the  tooth  at  least 
until  the  roots  are  fully  formed. 

Often  a  child  meets  with  some  accident  which  breaks  off  the  angle 
of  a  central  or  lateral  incisor.     To  restore  the  angle  sometimes  necessi- 


Fig    144.      Post-collar   crown   on   a   temporary   cuspid   root.      The   permanent   cuspid    erupted   down 

to  the   post  of  the   crown.      The   dark   shadows  in   the   region   of   the   temporary   cuspid   crown   are 

numbers  used   to  mark  the  negative.      (Radiograph   by   Kells,  of  New  Orleans.) 

tates  the  removal  of  the  pulp  and  the  placing  of  a  post  in  the  canal.  The 
question  should  always  be  raised,  "is  the  tooth's  root  fully  formed?" 
If  it  is,  we  may  proceed  with  the  devitalization,  but  if  not,  some  tem- 
porary restoration  should  be  made  and  the  pulp  conserved  until  it  has 
fulfilled  its  function  of  root  development.  Whether  the  root  is  fully 
formed  or  not  can  be  determined  only  by  the  use  of  the  X-rays. 

In  a  child's  mouth  we  occasionally  find  an  anterior  tooth  so  badly 
decayed  that  crowning  is  indicated.  Again  we  are  confronted  with  the 
question,  "is  the  root  fully  formed?"  And  whether  we  should  devitalize 
and  crown  the  tooth  or  keep  it  patched  with  cement  for  a  year  or  so 
depends  entirely  upon  the  answer  which  the  radiograph  may  make  to 
this  question. 

4.    to  Determine  UPbetber  a  tooth  be  One  of  the  Primary  or  Secondary  Set. 

What  treatment  we  give  a  tooth  depends  very  largely  on  whether 
it  be  of  the  permanent  or  deciduous  set.  If  a  man  knows  his  dental 
anatomy  as  well  as  he  should  it  is  usually  easy  for  him  to  determine 
whether  a  tooth  be  a  primary  or  secondary  one.  Occasionally,  how- 
ever, we  find  a  tooth   (usually  an  upper  lateral  incisor)    that  looks  as 


]'._>  DENTAL   RADIOGRAPHY 

much  like  a  member  of  one  set  as  the  other  and  the  radiograph  must  be 
used  to  arrive  at  a  definite  conclusion.  To  mistake  a  permanent  tooth 
for  a  deciduous  one  and  extract  it  (Fig.  130)  is  an  inexcusable  and  dis- 
astrous blunder. 

Sometimes  a  tooth  is  so  badly  decayed  (the  crown  may  be  entirely 
destroyed)  that  it  is  impossible  to  determine  by  simple  ocular  observa- 
tion whether  it  be  a  temporary  or  a  permanent  one.  The  radiograph  can 
be  used  to  great  advantage  in  such  cases.  If  the  carious  tooth  be  one 
of  the  temporary  set,  with  the  succedaneous  tooth  ready  to  take  its  place, 
it  should  be  extracted.  If  the  carious  tooth  be  a  permanent  ones  the 
radiograph  shows  the  size  and  condition  of  its  roots. 

Case — a  post-collar  cuspid  crown  became  loose. 
Tig.    144.  A  radiograph   (Fig.  144)   was  made  and  shows  that 

the  crown  is  placed  on  a  temporary  cuspid  root.  Part 
of  the  root  of  the  temporary  tooth  is  resorbed  and  the  permanent  cuspid 
has  erupted  down  to  the  end  of  the  post  of  the  crown.  The  very  dark 
shadows  in  the  region  of  the  temporary  cuspid  crown  are  caused  by  lead 
numbers  placed  against  the  film  packet  to  mark  the  negative. 

5.    to  Determine  Ulben  to  extract  temporary  teeth. 

The  best  rule  ever  formulated  for  the  extrac- 
f  jg.  145.  tion  of  deciduous  teeth  reads,  "Extract  a  deciduous 

tooth  only  when  its  successor  is  ready  to  take  its 
place."  There  are  many  cases  where  the  operator  is  able  to  detect  the 
presence  of  the  succedaneous  teeth  by  ocular  and  digital  examination. 
In  about  as  many  cases,  however,  the  only  way  to  determine  the  presence 
of  such  teeth  is  by  the  use  of  the  radiograph.  Thus  the  rule  just  quoted 
is  one  which,  when  followed,  necessitates  the  use  of  the  radiograph.  Fig. 
145  is  of  a  case  where  extraction  of  the  temporary  first  molar  is  indicated, 
and  extraction  of  the  temporary  second  molar  is  contraindicated.  The 
temporary  second  molar  should  not  be  removed  for  a  year  or  so — not 
until  the  second  bicuspid  is  just  ready  to  take  its  place. 

Often  in  practice  we  are  confronted  with  abscessed  temporary  teeth. 
The  age  of  the  patient  is  such  that  we  cannot  decide  whether  the  tieeth 
are  loose  as  a  result  of  the  abscessed  condition,  or  because  of  resorption 
of  the  roots  and  the  presence  of  the  succedaneous  teeth.  A  radiograph 
of  the  case  will  enable  us  to  decide,  and  our  treatment  will  be  governed 
accordingly.  Not  only  will  the  radiograph  show  the  operator  when  de- 
ciduous teeth  should  be  removed,  but  will  aid  him  in  their  removal — 
especially  in  cases  where  the  temporary  teeth  are  badly  decayed — by 
-bowing  the  exact  size  and  location  of  the  temporary  teeth's  roots  and 
the  position  of  the  succedaneous  teeth. 


THE  USES  OE  THE  RADIOGRAPH  IN  DENTISTRY     163 

6.    Co  Show  the  Orthodontist  Ulhen  Re  may  move  the  Coming  Permanent  teeth  by 
moving  the  Deciduous  teeth. 

It  impressed  me  very  much  when  I  first  heard  of  radiographically 
observing,  and  then  regulating,  teeth  before  their  eruption.  I  heard  of 
this  in  a  lecture  by  Dr.  Ottolengui.     I  quote  Dr.  Ottolengui : 

"One  of  the  difficult  operations  which  confronts 

fig.  14&.  the  orthodontist  at  times  is  the  bodily  movement  of 

the  bicuspids  buccally.     Very  often  in  the  past  at- 


Fig.   145.     This   picture    shows    that    the    temporary    first    molar    should    be    extracted.       The    tem- 
porary  second   molar   should    not   be   extracted    for    a   year   or    so,    when    the    second    bicuspid    will 
be   just   ready   to    take   its   place.      (Radiograph    by   Lewis,    of   Chicago.) 


tempts  to  widen  the  arch,  after  the  eruption  of  the  bicuspids,  has  resulted 
in  tipping  the  crowns  buccally,  the  apices  of  roots  remaining  in  the  orig- 
inal apical  arch.  Hence,  one  of  the  chief  advantages  of  early  orthodontic 
interference  lies  in  the  fact  that  the  temporary  molars  may  be  moved 
buccally,  carrying  with  them  the  underlying  bicuspids,  and  this  advantage 
is  made  more  clear  if  it  be  recalled  that  at  this  period  the  bicuspid  roots 
are  but  partly  formed.  Even  when  the  roots  of  the  temporary  molars 
are  already  considerably  absorbed,  still  enough  may  be  left  to  serve  to 
deflect  the  oncoming  bicuspids  in  the  direction  desired. 

"This  slide  (Fig.  146),  from  the  collection  of  Dr.  Matthew  Oyer 
(radiograph  by  Pancoast,  of  Philadelphia),  shows  nicely  the  usual  rela- 
tion of  the  erupting  bicuspids  to  their  predecessors,  the  temporary  molars. 
It  will  be  noted  that  the  apices  of  the  bicuspids  are  still  unformed,  and  it 
is  clear  that  if  these  teeth  can  be  led  into  proper  positions  during  eruption r 
the  formation  of  the  apices  afterward  affords  the  most  permanent  'reten- 
tion.' A  casual  glance  at  the  upper  temporary  molars  might  create  a 
doubt  as  to  the  probability  of  moving  the  unerupted  bicuspids,  but  there 
is  an  easily  overlooked  factor,  viz.,  the  palatal  roots  of  these  molars  do 


i&l 


DENTAL  RADIOGRAPHY 


not  show  in  radiographs  of  this  region  at  this  period,  because  they  lie  be- 
hind the  crowns  of  the  bicuspids  ;  that  is  to  say  'behind,'  in  relation  to 
the  source  of  light,  the  X-ray  tube." 


Fig.  n<;, 


Radiograph   made  to  show   relation   of  temporary  molar  roots  to  advancing  bicuspids. 
(Collection  of  Dr.  Cryer.     Radiograph   by  Pancoast,  of  Philadelphia.) 


7.    to  Obscroe  mooing  teeth. 

Fig.  147  demonstrates  the  congenital  absence  of 

Tifl$-  147,  148  and  149.    the  upper  lateral  incisors.   The  orthodontic  appliance, 

seen   in   the   radiograph,   is  being  used  to  draw   the 

centrals  together.     It  was  highly  important  in  this  case  that  the  teeth  be 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     165 

moved  through  the  alveolar  process  en  masse,  and  not  tipped.  The 
movement  desired  was  one  which  would  make  the  roots  parallel  when 
the  crowns  of  the  teeth  came  together,  so  that  posts  could  be  set  in  the 
canals  of  the  central  incisors,  and  a  bridge  made  to  restore  the  lost  lat- 
erals. Fig.  148  was  taken  about  a  month  after  Fig.  147.  It  shows  that 
the  teeth  had  been  moved  together,  but  there  was  too  much  tipping  of  the 


Fig.   147.  Fig.   148.  Fig.   149. 

Fig.  147.     Congenital   absence  of  upper  lateral   incisors.     The   orthodontic  appliance   seen   is  being 

used   to    draw   the    central   incisors    together. 
Fig.   148.     This  radiograph   was   made   one  month   after   Fig.  147.      It   will   be   seen   that   there  has 

been  considerable   movement   of   the   teeth.     The   left   central   is   tipped   considerably. 
Fig.    149.      Made   one   month    after   Fig.   148.      The    central    incisors   are   together    and    their    roots 

almost   parallel. 


left  incisor — not  enough  movement  of  the  tooth  at  the  apex  of  the  root, 
compared  to  the  movement  of  the  crown.  It,  therefore,  became  necessary 
to  modify  the  force  which  was  being  used.  This  was  done,  and  Fig.  149 
shows  the  teeth  together  and  the  roots  almost  parallel. 

A  case  in  the  practice  of  Dr.  C.  Edmund  Kells, 
TiflS.  ISO,  151  and  152.  Jr.,  and  reported  by  him  in  the  May  number  of 
Items  of  Interest,  191  i.  Fig.  150  shows  a  mal- 
posed  permanent  cuspid  above  the  temporary  cuspid,  the  root  of  which 
is  somewhat  resorbed.  Age  of  patient,  eleven  years.  Fig.  151  was 
made  one  year  and  seven  months  after  Fig.  150.  "Compare  this  pic- 
ture with  Fig.  150,  and  it  will  be  seen  that  the  permanent  cuspid  has 
migrated  in  a  line  with  its  long  axis,"  causing  resorption  of  the  perma- 
nent lateral  root.  The  temporary  cuspid  was  extracted,  but  the  perma- 
nent tooth  did  not  erupt  into  its  position  in  the  arch.  It  was,  therefore, 
concluded  that  the  tooth  "would  have  to  be  brought  down  by  some 
mechanical  means."  Accordingly,  the  gum  tissue  and  overlving  process 
were  "slit  down  to  the   cuspid  and   then  gently   spread   apart,   and  the 


1 66 


DENTAL  RADIOGRAPHY 


cuspid  was  exposed  to  view."  A  piece  of  iridio-platinmn  wire  was 
then  shaped,  as  shown  in  Fig.  152,  and  the  hook  was  worked  supposedly 
under  the  mesial  prominence  of  the  cuspid,  and  a  rubber  ring  attached 
to  the  loop  on  the  other  end,  and  secured  to  a  lug  on  the  molar  band,  all 
as  shown  in  Fig.  152.  which  is  a  skiagraph  of  the  case  with  the  appliance 


Fig.  150.  Fig.    151. 

Fig.    150.      Malposed,    permanent    cuspid    above    the    temporary    cuspid,    the    root    of    the    latter 

somewhat   resc-bed. 

Fig.    1"il.      Same   as   Fig.    150   one   year  and   seven   months   latT.      Observe   that   the   cuspid    has 

migrated   in   the   line   of  its  long  axis.     The  permanent   lateral   root   is  badly    resorbed. 


Pig,    152.     Same  as   I  igs.   150  an. I   ] :.  l    after  removal  of  the  temporary  cuspid.     The  wire   hooked 
the    cusp    of    the    tootb     was    thought    to    be    placed    over    the    mesial    prominence    until    the 
radiograph   was  made. 


in  position.  Imagine  my  surprise  to  find  by  this  picture  that  the  hook 
nol  anywhere  near  where  I  had  thought  I  put  it.  [nstead  <>f  being 
well  up  under  the  medal  prominence,  it  was  merely  caught  under  the 
point  of  tin-  tooth,  and,  «>f  course,  it  slipped  off  shortly  after  the  patient 
left  the  office.  Upon  her  return  a  hook  -\x  of  an  inch  longer  was  fitted 
in  place,  and  this  time,  with  a  radiograph  as  a  guide,  there  was  no  mis- 
take  about  its  placement.    The  appliance  was  worn  for  several  weeks,  at 


THE   I'SES  OF  THE  RADIOGRAPH  IN  DENTISTRY     167 


the  end  of  which  time  the  point  of  the  cuspid  having  been  brought  to  the 
surface  of  the  gum,  it  was  removed  and  the  tooth  allowed  to  erupt  by  its 
own  volition.  Despite  the  great  destruction  of  its  root  the  lateral  re- 
mains firm  and  apparently  healthy. 


Tig.  is3. 


8.    Tn  Cases  of  Supernumerary  Ceetb. 

A  case  in  the  practice  of  Dr.  B.  S.  Partridge, 
Chicago.  Patient's  age,  twelve  years.  The  teeth 
were  being  regulated,  and  the  radiograph.  Fig.  151, 


Fig.    153.  .  Fig.   154. 

Fig.    153.      A    and    B,    supernumerary    tooth    bodies.      C,    the    crown    of    the    temporary    cuspid. 

D,   the   permanent   cuspid.      (Radiograph  by   Lewis,   of   Chicago.) 

Fig.   154.      A  and   B  are  supernumerary  teeth.      (Radiograph  by  Lewis,   of   Chicago.) 


was  taken  to  determine  the  presence  or  absence  of  the  permanent  lower 
cuspid.  A  little  supernumerary  tooth  (A)  could  be  seen  in  the  mouth 
occupying  a  part  of  the  space  which  should  have  been  occupied  by  the 
permanent  cuspid.  The  two  shadows  marked  "B"  are  two  more  super- 
numerary tooth  bodies.  The  larger  shadow  marked  "C"  is  the  crown  of 
the  temporary  cuspid,  which  had  never  erupted.  The  large  shadow  to 
the  left,  marked  "D,"  is  the  permanent  cuspid  pressing  against  the  side 
of  the  lateral  at  the  apex  of  its  root.  The  three  supernumerary  bodies 
and  the  crown  of  the  temporary  cuspid  (the  root  was  resorbed)  were 
removed,  allowing  the  permanent  cuspid  to  erupt. 

Just  lingually  to  each  central  incisor  is  a  super- 
Tig.  154.  numerary    tooth.      One    (A)    could   be    seen   in   the 
mouth,    but    there    was    no    evidence    of    the    other. 
Neither  central  nor  lateral  incisor  roots  are  as  yet  fully  formed,  and  the 


108 


DENTAL  RADIOGRAPHY 


laterals  have  not  yet  erupted.  Indeed,  before  the  picture  was  made,  it 
seemed  that  a  peg-shaped  lateral  was  erupting  just  lingually  to  the  cen- 
tral.    The  radiograph  shows  this  tooth  to  be  supernumerary. 

Dr.  T.  W.  Brophv.  of  Chicago,  reports  a  case  of  insistent  suppura- 
tion due  to  an  impacted  supernumerary  tooth,  which  was  found  by  the 
use  of  the  radiograph.  Dr.  Brophv  calls  attention  to  the  fact  that  a  cor- 
rect and  definite  diagnosis  could  not  have  been  made  by  any  means  at  our 
command  except  the  X-rays.  The  case  recovered  promptly  upon  removal 
of  the  supernumerary  tooth.  I  regret  that  I  have  been  unable  to  obtain 
radiographs  of  this  case. 

Tig.  155.  An  impacted  upper  fourth  molar. 


Fig.    155.  Fig.   156. 

Fig.    155.      An   impacted   upper    fourth   molar. 
Fig.   150.     A  supernumerary  tooth  in  the  canal  of  a  cuspid  tooth.      (Radiograph  by  Clarence  Van 

Woert,    of    New    York    City.) 


To  me  this  is  a  most  remarkable  case — a  super- 
Tig.  156.  numerary  tooth  in  the  canal  of  a  cuspid  tooth — a 
tooth  inside  of  a  tooth.  The  supernumerary  tooth 
has  a  root  canal,  and  the  crown  is  covered  with  enamel.  There  is  no 
doubt  of  the  fact  stated,  because  Dr.  Van  Woert,  after  radiographing  the 
case,  drilled  into  the  permanent  cuspid  and  found  the  enamel-covered 
supernumerary  within.  The  radiograph  is  not  as  good  as  I  wish  it  were. 
The  upper  two-thirds  of  the  roots  of  the  teeth  shows  fairly  well  but  tbere 
is  a  confusion  of  shadows  in  the  lower  third  and  m  the  crown. 

9.    Tn  eases  of  Impacted  teeth  as  an  Aid  in  extraction. 

Impacted,     lower,    third     molar    tipped     to    the 
Tig.  157.  mesial.     The  picture  shows  that  in  this  case  a  knife- 

edge  stone  in  the  dental  engine  could  he  used  to  ad- 
vantage, rutting  away  the  mesio-OCClusal  portion  of  the  third  molar,  and 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     169 

so  greatly  facilitating  the  removal  of  the  tooth.  Observe  the  absorption 
of  the  distal  surface  of  the  second  molar  (the  light  area),  due  to  pressure 
against  it;  and  the  large  abscessed  cavity  (light  area)  between  the  sec- 
ond and  third  molars,  extending  down  to  the  apex  of  the  second  molar. 
This  radiograph  is  of  particular  interest,  because  it  shows  so  clearly  an 
abscess  caused  by  impaction. 

That   the   pressure   of   an   impacted   tooth   may 

Tigs.  158  and  159.       cau?e    abSOrption    of    the    tooth    against    which    the 

pressure  is  brought  to  bear,  is  further  illustrated  in  Figs.  158  and  159. 


Fig.    157.  Fig.   158. 

Fig.  157.  An  impacted  lower  third  molar.  The  light  area  between  the  second  and  third  molars 
represents  a  destruction  of  bony  tissue,  arrow  A.  Arrow  B  points  to  a  light  area,  which  repre- 
sents the  absorption  of  the  second  molar.  (Radiograph  by  Blum,  of  New  York  City.) 
Fig.  158.  An  impacted  upper  third  molar.  The  arrow  points  to  a  light  area  representing 
absorption  of  the  upper  second  molar.  Notice  the  very  poor  filling  encroaching  on  the  pulp  of 
the  first  molar  and  filling  the  interproximal  space  between  the  first  and  second  molar.  (Radio- 
graph  by   Ream,   of  Chicago.) 

In  Fig.  158  the  arrow  points  to  a  light  area  representing  absorption 
of  the  upper  second  molar,  due  to  the  pressure  of  the  third  molar  against 
it.  A  study  of  this  radiograph  gives  the  dental  surgeon  a  good  idea  of 
how  he  should  apply  his  force  in  extraction. 

Fig.  159  is  a  case  of  Dr.  Oyer's.  I  quote  Dr.  Oyer:  Fig.  159 
"shows  an  impacted,  lower,  third  molar  resting  against  the  posterior  root 
of  the  second  molar.  It  will  be  seen  that  the  root  of  the  second  molar  is 
much  absorbed,  which  caused  considerable  trouble.  Removal  of  the  sec- 
ond molar  gave  relief  to  the  patient.  .  .  .  The  upper  third  molar  is 
in  an  awkward  position." 

Figs.   160  and   161    show   impacted  upper  third 
TlflS.  160  and  161.        molars.     The  value  of  these  radiographs  to  the  ope- 
rator, about  to  extract,  is  apparent. 

This  radiograph   (Fig.   162)   shows  the  surgeon 

fig.  |^2.  just  how  much  bone  must  be  dissected  away  before 

the  malposed  tooth  can  be  removed.     Patients  seldom 


lyo  DENTAL    RADIOGRAPHY 

know  that  the  removal  of  a  tooth  is  not  always  a  simple  operation.  They 
are  therefore  inclined  to  blame  the  operator  if  the  tooth  is  not  quickly 
removed,  instead  of  crediting  him  with  working  dexterously  on  a  difficult 
operation.     They  are  likewise  unwilling  to  pay  a  fee  in  proportion  to  the 


■  1   uppei    and   lower   third  molar.     Absorption  of  the  distal   root  of  the  lower 
second   molar.      (Radiograph    by    I'ancoast,   of    Philadelphia.) 

difficult)  "i  the  operation,  as  compared  t<>  other  operations.  The  removal 
oT  the  third  molar,  shown  in  Fig.  162,  is  a  more  difficult  operation  than  t lie 
removal  of  a  vermiform  appendix.  By  showing  patients  radiographs  of 
such  cases  the  dentist  will  gain  their  earnest,  intelligent  co-operation. 
They  will  know  just  what  is  done  for  them,  and  for  the  first  time  in  their 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     171 

lives  they  will  understand  that  the  extraction  of  a  tooth  may  be  a  serious, 
difficult  and  expensive  operation. 

The  following  report  of  this  case  is  by  Dr.  F.  K. 

Tig.  163.  Ream,  of  Chicago.   "Patient's  age,  seventy-two  years. 

Symptoms:    Swelling  near  symphysis  thought  to  be 

the  result  of  wearing  an  artificial  denture.    Considerable  pain.    Diagnosed 


Fig.   160.  Fig.   161. 

Fig.    160.      Impacted    upper    third    molar.     (Radiograph    by    Lewis,    of    Chicago.) 

Fig.    161.      Impacted    upper    third   molar.      Notice    the    difference    in    the    position    of   the    impacted 

tooth   shown   in   this   case  and  in    Fig.    160.      (Radiograph   by   Blum,   of   New    York   City.) 


Fig.   162. 


Fig.    163. 


Fig.  162.  Impacted  lower  third  molar  with  its  occlusal  surface  presenting  mesially.  The 
radiograph  shows    the    dental    surgeon    how    much    bone    must    be    burred    away    before    the    tooth 

can  be  removed.      (Radiograph  by   Ream,  of  Chicago.) 

Fig.    163.      Impacted    bicuspid    in    an    otherwise    edentulous    mouth.      Age    of    patient,    72    years. 

(Radiograph  by  Ream,   of  Chicago.) 

cancerous  by  surgeons,  and  patient  advised  to  go  to  the  hospital  for  opera- 
tion. The  radiograph  (Fig.  163)  shows  an  impacted  bicuspid  in  the 
otherwise  edentulous  jaw.  Operation  :  Alveolar  process  burred  away 
and  tooth  removed.     Result:    Immediate  and  complete  recovery." 


I--' 


DENTAL    RADIOGRAPHY 


tig.  104  is  a  case  of  Dr.  Oyer's.     I  quote  Dr. 
Tig.  it>4.  Cryer:     Fig.  1(4  "shows  a  lower  third  molar  passing 

under  the  second  molar  and  becoming  lodged  be- 
tween the  first  and  second  molar,  the  crown  of  the  third  molar  pushing 
against  the  root  of  the  first  molar.  The  first  molar  was  extracted,  which 
cleared  up  the  neuralgia,  and  the  third  molar  pushed  up  into  the  place 
1  'f  the  first  molar." 


Fig.    104.      Lower    third    molar    lodged    between    the    first    and    second    molars.       (Radiograph    by 

Pancoast,  of  Philadelphia.) 

Fig.    165  is  also  a  case  of   Dr.   Oyer's.     The 

fig.  its.  radiograph    shows    an    impacted    upper   third   molar, 

with  the  occlusal  surface  presenting  upwards.     Dr. 

Oyer's  remarks  concerning  this  case  are  interesting.     I  quote  Dr.  Cryer: 

[65  "shows  the  occluding  surface  of  the  upper  third  molar  pointing 

upward    towards    the  posterior   portion   of    the   orbit.      The   patient   had 

been  suffering  from  disturbance  of  the  eye  for  a  long  time.    Considerable 

improvement  took  place  in  the  eye  soon  after  extraction  of  the  inverted 

tooth." 

10.    Co  Determine  the  number  of  Canals  in  Some  teeth. 
It  will  be  noticed  thai   I  say  "to  determine  the  number  of  canals  in 
tome  teeth."    Of  course,  it  i>  not  necessary  to  use  the  radiograph  each 


THE  USES  OF   THE  RADIOGRAPH  IN  DENTISTRY     173 

time  we  open  into  a  tooth  to  learn  how  many  canals  that  tooth  may  have. 
But  occasionally  I  do  find  it  necessary  or  expedient  to  use  the  radiograph 
to  verify  or  disprove  the  existence  of  some  unusual  condition  suspected. 


Fig.  i«; 


Impacted    upper   third   molar  with   the   occlusal    surface   pointing   upward.      (Radiograph 
by   Pancoast,   of   Philadelphia.) 


Case :     An  upper  first  molar  in  which  but  one 
Tifl.  166.  small  canal  could  be  found.    After  searching  for  the 

other  two  canals  for  a  few  minutes,  the  one  canal 
was  filled  with  gutta-percha,  and  a  radiograph  made  (Fig.  166)  ;  this 
shows  that  the  tooth  had  but  one  canal.  In  this  case  the  radiograph  saved 
considerable  work  and  worry  on  the  part  of  the  operator.  I  have  known 
second  and  third  molars  to  have  only  one  canal,  but  this  is  the  only  case 
I  have  ever  encountered  in  which  a  first  molar  had  but  one  canal. 

This  case  was  in  the  hands  of  one  of  the  most 

Tig.  167.  expert   operators   in   Indianapolis.      The   lower   first 

bicuspid  had  been  devitalized,  and  the  pulp  removed, 


174  DENTAL   RADIOGRAPHY 

but  the  tooth  remained  sore.  Radiography  was  resorted  to  to  learn,  if 
possible,  the  cause  of  the  persistent  pericementitis.  A  piece  of  ligature 
wire,  such  as  is  used  by  orthodontists,  was  placed  in  the  canal  and  radio- 
graph Fig.  167  made.  The  wire  follows  the  enlarged  canal.  But  this 
particular  tooth  happens  to  have  two  canals.  The  unopened  canal  is  seen 
to  the  distal  of  the  wire.  If  a  man,  having  the  skill  of  the  operator  who 
handled  this  case,  misses  a  canal,  as  this  man  did,  then  I  firmly  believe 
that  the  mistake  is  one  that  anv  man,  however  skillful,  is  liable  to  make. 


Fig.   166.  Fig.  167. 

Fig.    1GG.      Upper    first    molar    with    but    one    canal    which    is    filled. 

Fig.    1G7.      The   dark    streak   in    the    first   bicuspid   is   a    wire    passing   into    the    canal.      This    tooth 

has  another  canal,    which  can   be   seen   as  a   light  streak   distal! j'    to   the    wire.      The  more   or   less 

oval   dark   spot   at  the   neck   of   the    first   bicuspid   is   a  buccal    cervical    filling.      The   cavity    in    the 

crown  of  the  tooth  is  stopped  up  with  gutta-percha. 


Let  me  say  here  that  a  lower  bicuspid,  or  cuspid  with  two  canals,  is 
not  such  an  unusual  occurrence,  as  it  is  generally  believed  to  be.  Men 
have  shown  me  such  teeth,  and  spoken  of  them  as  though  they  were  rare 
anomalies.  As  a  teacher  of  operative  technic,  I  devote  a  part  of  my  time 
to  the  dissection  of  teeth.  In  this  work  I  handle  thousands  of  disasso- 
ciated human  teeth.  In  my  work  of  last  year,  for  example,  I  estimate 
that  I  observed  six  to  eight  thousand  teeth.  And  among  these  I  noticed 
not  less  than  seven  lower  cuspids  and  five  lower  bicuspids  with  two 
canals  each. 

Without  printing  the  radiograph,  which  is  not  a  very  good  one,  I 
quote  the  legend  which  appears  beneath  it  in  the  last  edition  of  Buckley's 
"Modern  Dental  Materia  Medica,  Pharmacology  and  Therapeutics."  "In 
this  case  the  author  desires  to  insert  a  bridge.  On  opening  into  the  third 
molar  an<l  second  bicuspid,  which  teeth  were  to  be  used  for  the  abut- 
ments, we  were  unable  to  finrl  any  canals  in  the  bicuspid,  and  only  a  small 
canal  in  the  molar.     The  skiagraph  confirms  the  clinical  findings." 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     175 

11.    Hs  an  Jtid  in  Tilling  the  Canals  of  teeth  with  Carge  Apical  foramina. 

To   demonstrate   this   use   of    the   radiograph   a 
Tig.  16$.  central    incisor    with    a    large    apical    foramen    was 

chosen,  and  an  orthodontic  ligature  wire  passed  into 
the  canal  until  the  patient  received  sensation.  The  worthlessness  of  the 
"sensation  test,"  as  a  guide  in  filling  to  the  apex  of  canals  is  demon strated 
by  Fig.  168,  which  shows  the  wire  penetrating  the  tissues  four  or  five 
millimeters  beyond  the  apex  of  the  tooth.  After  the  radiograph  (Fig. 
168)  was  made,  the  wire  was  removed,  and  that  part  of  it  penetrating  the 
apex  cut  off",  or  as  nearly  as  could  be  judged  from  the  appearance  of  the 
radiograph. 


Fig.  168.  Fig.   169.  Fig.  170. 

Fig.   168.     A  wire  passing  through  a  large  apical  foramen  in  an  upper,   central   incisor,  extending 
several  millimeters  into  the  tissues  above  the  apex  of  the   root. 

Fig.    169.      The    same   case   as    Fig.   168,    after   the    wire   has   been    removed,    a   part    of   it    cut   off 
and  reinserted  into  the  canal.     The  wire  reaches  just  to  the  apical   foramen. 

Fig.  170.  The  same  case  as  Figs.  168  and  169,  showing  a  canal  filling  of  gutta-percha  closing 
the  apical  foramen,  not  penetratirg  through  it.  and  not  leaving  a  little  of  the  canal  unfilled 
at  the  apex  of  the  root.     The  entire  canal  is  not  filled,  because  there  is  to  be  a  post  set  in  it. 

Next  the  shortened  wire  was  reinserted  and  an- 

Tifl.  169.  other  radiograph  (Fig.  169)  made.    This  shows  that 

my  judgment  in  cutting  off  the  wire  in  this  particular 

case  was  unusually  good.    The  wire  reaches  just  to  the  apex.     It  may  be 

necessary  to  make  two  or  three  trials  before  the  wire  is  placed  just  to 

the  apex. 

With  the  length  of  the  wire  as  a  guide  to  the 
fig.  170.  length  of  the  root,  the  proper  distance  was  measured 

on  a  canal  plugger,  and  the  distance  marked  on  the 
plugger  by  passing  it  through  a  little  piece  of  base-plate  gutta-percha, 
stopping  the  gutta-percha  on  the  plugger  at  a  distance  from  its  end  equiv- 
alent to  the  length  of  the  wire.     The  end  of  the  canal  plugger  was  then 


176  DENTAL   RADIOGRAPHY 

warmed  slightly,  and  brought  in  contact  with  a  small  piece  of  gutta- 
percha canal  point.  With  the  piece  of  gutta-percha  so  fastened  on  the 
canal  plugger,  it  was  carried  into  the  canal  a  sufficient  distance  to  reach, 
but  not  pass,  beyond  the  apex.  (Fig.  170.)  A  slight  twist  of  the  plugger 
will  disengage  it  from  the  gutta-percha,  when  the  latter  may  be  tamped 
firmly,  but  not  too  forcibly,  to  place.  Xo  further  filling  of  the  canal  was 
done  in  this  case,  the  canal  being  left  open  to  receive  a  post.  The  method 
just  described  is  positively  the  only  one  which  enables  the  operator  to  fill 
canals  with  large  apical  foramina  perfectly. 


Fig.  171  Fig.  172  Kig.  173 

Fig.  171.  At  the  end  of  the  first  sitting  after  removal  of  the  pulp  from  the  lower  first 
molar.  The  dark  streaks  are  wires  passing  into  the  canals  as  far  as  they  (the  canals)  are 
enlarged — almost  to  the  apex  in  the  distal  and  about  one-half  the  distance  to  the  apex  in 
the    two    mesial.      The    dark    shadow    in    the    crown    of    the    tooth    is    gutta-percha,    used    to    stop 

up   the   cavity   and    hold   the    wires. 
Fig.   172.     The  same   case   as    Fig.   171    after   several   sittings.     The   wires   now   pass   well    to  the 

apex    in    all    canals. 
Fig.   173.     The  same  case  as  Figs.   171   and  172.     This  radiograph   shows  the   tooth   after  filling. 

What  will  happen  if  the  canal  filling  either  fails  to  reach  the  apex  or 
passes  a  little  beyond  it?  An  abscess  may  result.  If  the  canal  filling  fails 
to  reach  the  apical  foramen,  in  such  cases  as  the  one  just  described,  an 
abscess  is  sure  to  occur.  If  perfectly  aseptic  gutta-percha  is  used  as  a 
canal  filling,  and  the  tissues  above  the  apex  are  not  infected,  then  the 
passage  of  a  little  gutta-percha  into  the  apical  tissues  will  probably  not 
result  in  suppuration  or  even  inflammation,  so  well  do  tissues  tolerate 
gutta-percha.  Hut  the  fact  remains:  The  ideal  canal  filling  is  one  which 
fills  the  canals,  neither  falling  short  of  the  end  of  the  root  nor  passing 
beyond  it. 

12.  to  Ccam  if  Canals  Hrc  Open  and  enlarged  to  the  flpex  Before  Tilling,  and  to 
Observe  the  Canal  Tilling  After  the  Operation. 

Shows  a  lower  first  molar  at  the  end  of  the  first 

Tig.  171.  sitting,  after  the  extirpation  of  the  pulp.     The  wire 

i  the  dark  streak)   in  the  distal  canal  reaches  almost 


THE  USES  OF  THE  RAMOGRAI'll  IN  DENTISTRY     177 

to  the  apex  of  the  root.  The  two  wires  in  the  mesial  canals  penetrate  only 
about  one-half  the  distance  to  the  apex.  These  wires  pass  into  the  canals 
as  far  as  they  (the  canals)  are  enlarged.  Wires  are  placed  in  the  canals 
to  learn  to  what  depth  the  latter  are  enlarged,  because  the  wire  shows  so 
much  better  in  the  radiograph  than  the  open  canal.  In  fact,  the  wire  can 
be  seen  very  clearly  as  a  dark  streak  when  the  canal  itself  as  a  light  streak 
cannot  be  radiographed  at  all. 


Fig.    174.      Wire   passing    to   the   distal    through    a    perforation    in   the    upper    first    molar.       (Radio- 
graph   by     Blum    of    New     York    City.) 


Sufficient    enlargement   of    the    canals    required 
Tig.  172.  several  sittings.    The  technic  for  enlarging  the  canals 

consisted  of  pumping  sulphuric  acid  into  them,  neu- 
tralizing it,  then  reaming  them  out  with  thumb,  spiral  broaches.  Sul- 
phuric acid  was  sealed  in  the  mesial  canals  at  the  end  of  the  first  and 
second  sittings.  Fig.  172  shows  the  wires  well  to  the  apex  in  all  three 
canals. 

This    radiograph   shows   the   tooth   after   filling. 
Tig.  173.  Even  after  the  canals  are  enlarged  we  sometimes  fail 

to  reach  the  apex  with  the  gutta-percha  filling.  For 
this  reason  it  has  become  my  custom  lately  to  fill  only  a  part  of  the  canal, 
then  make  a  radiograph  to  see  that  the  filling  reaches  the  apex  before 
finishing  the  operation.  Dr.  M.  L.  Rhein,  of  New  York  City,  was,  as  far 
as  I  am  able  to  learn,  the  first  man  to  make  a  practice  of  using  the  radio- 
graph as  a  regular  routine  in  canal  work. 

The  advantages  in  using  the  radiograph  in  this  connection  are  as  fol- 
lows :  All  guesswork  is  eliminated — we  know  exactly  what  we  are  doing. 
If  the  canal  is  tortuous,  and  we  start  through  the  side  of  the  root,  the 
radiograph  shows  us  the  mistake,  keeps  us  from  making  a  perforation, 
and,  in  many  cases,  enables  us  to  follow  the  canal  to  the  true  apex.  If 
the  root  is  unusually  short  the  radiograph  keeps  us  from  going  through 


i-S 


/ ) EN TAL  RADIOGRAPH Y 


the  apex,  and  if  it  is  unusually  long  it  keeps  us  from  making  the  error  of 
not  penetrating  the  canal  far  enough.  The  radiograph  shows  patients 
just  what  is  being  done  for  them. 


Fig.    17.").      The    upper    arrow    points    to    a    pulp    nodule    in    the    lower    first    molar.       (Radiograph 

by     Pfahler    of     Philadelphia.) 


Fig.  176  Fig.  177 

Fig.    17»;.     The   arrow    points    to    a    pulp    nodule.      (Radiograph    by    Cummings    of    Boston  I 
Pig.    177.     Pulp    nodule    in    the    lower    firs!    molar.       (Radiograph    by    Lewis    of    Chicago.) 


When  a  'anal  tilling  fails  to  reach  the  apex  of  a  root  by  about  a 
millimeter,  this  does  nol  always  mean  thai  the  canal  has  not  been  properly 
enlarged  and  rilled.     For,  remember,  the  pulp  does  not  enter  the  root 

through  one  large   foramen,  hut  usually  through  several  minute  openings. 


THE  USES  OF  THE  RADIOGRAPH  l\  DENTISTRY     179 

So,  often,  the  extreme  apex  of  the  root  is  almost  solid  dentin  and  ce- 
mentum. 

Having  observed  quite  a  large  number  of  radiographs  in  the  last  few 
years,  allow  me  to  state  that  many,  altogether  too  many  in  our  profession, 
fail  to  enlarge  and  fill  to  their  apices  all  canals  which  really  could,  and 
should,  be  so  treated.  There  are,  perhaps,  some  cases  where  the  buccal 
canals  of  upper  molars  and  the  mesial  canals  of  lower  molars  simply  can- 
not be  enlarged  to  their  apices.  But  this  fact  is  no  excuse  for  enlarging 
and  filling  only  the  upper  third  of  such  canals.  (Fig.  165,  lower  first 
molar.)  The  stock  excuse  for  poor  canal  work  is  "our  patients  will  not 
pay  a  fee  sufficiently  large  to  enable  us  to  give  the  necessary  time  to  the 
work."  But  do  those  who  thus  excuse  themselves  really  give  their  pa- 
tients any  choice  in  the  matter?  If  one  should  show  a  patient  a  radio- 
graph demonstrating  the  fact  that  he  had  only  penetrated  the  canals  about 
one-third  their  length,  then  explain  why  he  should  go  farther,  and  why  it 
would  take  time  to  do  so,  would  the  patient  say,  "Oh!  let  'er  go,"  or 
would  he  or  she  say,  "I  want  done  whatever  is  best?" 

It  is  extremely  difficult  to  radiograph  the  buccal  roots  of  upper 
molars. 

13.    to  Determine  Whether  an  Opening  Leading  from  a  Pulp  Chamber  Be  a 
Canal  or  a  Perforation. 

When  one  opens  the  tooth  himself,  and  does  not  use  a  small,  round 
bur  on  the  floor  of  the  pulp  chamber,  he  may  feel  certain  that  any  open- 
ing found  must  be  a  canal.  But  in  cases  'where  the  pulp  chamber  has 
been  opened  by  another  operator,  it  is  often  impossible  to  decide  whether 
an  opening  leading  from  the  pulp  chamber  be  the  mouth  of  a  canal  or  a 
perforation  through  the  tooth.  Likewise  in  cases  where  decay  has  attacked 
the  walls  and  floors  of  the  pulp  chamber,  almost  destroying  them,  it  is 
sometimes  difficult  to  differentiate  between  a  canal  and  a  perforation. 
Pass  a  wire  through  the  opening  and  make  a  radiograph. 

A  wire  passing  to  the  distal  through  a  perfora- 
tion in  the  upper  first  molar. 

14.    Tn  Cases  of  Pulp  Stones  (nodules). 

There  has  been  a  great  deal  of  dispute  as  to  whether  or  not  pulp 
nodules  can  be  shown  radiographicallv.  The  right  answer  is  in  the  affirm- 
ative. 

The  upper  arrow  points  to  a  large  pulp  nodule 
in  the  lower  first  molar.     Age  of  patient,  eight. 

A  case  in  the  practice  of  Dr.  Chas.  E.  Patten. 
Tig.  176.  The  patient,  female,  age  forty,  suffered  from  inter- 

mittent attacks  of  severe  pain  in  the  region  of  the 


[8o 


DENTAL   RADIOGRAPHY 


upper  bicuspids  and  first  molar.  A  radiograph  was  made  (Fig.  176)  and 
shows  a  shadow  in  the  pulp  chamber  of  the  first  molar.  The  molar  was 
devitalized  and  a  pulp  nodule,  located  at  the  mouth  of  the  lingual  canal, 
removed.  The  canals  were  then  enlarged  and  filled.  Result :  Complete 
cessation  of  recurrent  pain. 

A  case  in  the  practice  of  Dr.  H.  H.  Schuhmann, 
Tig.  177.  or  Chicago.    I  quote  Dr.  Schuhmann:    "Mr.  K.  suf- 

fered from  severe  pains  under  left  side  and  at  angle 
of  jaw.     Pains  intermittent  and   intense  at  night.     No  reaction  to  per- 


Fig.  178 


Fig.  170 


Fig.     ITS.     The    arrow    points    to    what    might    he    mistaken     for    a    pulp    nodule.       The    shadow 

is,    however,    an    amalgam    filling    on    the    buccal     at     the    cervical. 

Fig.     179.      Simple     occlusal     filling    in     the     molar,     encroaching     on     the     pulp. 


cussion  or  application  of  heat  or  cold.  Radiograph  showed  what  I  took 
to  be  a  pulp  stone,  and.  upon  opening  the  tooth  and  applying  arsenic  three 
times  the  stone  was  removed.  Patient  now  has  no  neuralgic  pains  what- 
ever." 

In  this  radiograph  the  arrow  points  to  a  shadow 
fig.  i78.  which   might  he   mistaken   for  a  pulp  nodule.      The 

shadow  is,  however,  not  a  pulp  stone,  it  is  a  small 
amalgam  tilling  on  the  buccal  surface  at  the  cervical  margin. 

The  radiographs  which  I  have  printed  demonstrate  that  the  pulp 
nodules  ''an  he  radiographed.  I  may  add  that  personally  1  have  radio- 
graphed a  number  of  cases  successfully.  But,  let  me  confess,  1  have  not 
as  yet  produced  as  clear  a  picture  as  the  ones  shown  in  Figs.  175,  176 
and   177. 

is.    In  Cases  of  Secondary  Dentin  Being  Deposited  and  Pinching  the  Pulp. 

This  use  was  recently  suggested  in  a  dental  magazine  by  Dr.  Cryer. 
Such  a  condition  as  tin-  one  referred  to  might  exist  and  he  responsible  for 
neuralgia  or  other  nerve  disorder-.     Likewise  it  could  probably  be  ob- 


THE  USES  OF   THE  RADIOGRAPH  IN  DENTISTRY     181 

served  radiographically.     At  the  present  time,  however,  I  am  unable  to 
show  a  radiograph  of  such  a  case. 

16.    Co  Cearn  if  the  Tilling  in  the  Crown  of  a  tooth  encroaches  on  the  Pulp. 

Case:     Neuralgic  pains  in  the  lower  left  side  of 
fig.  179.  face.     Thought  to  be  due  to  a  necrotic  condition  of 

the  bone  in  the  region  of  the  lower  first  molar,  which 
had  recently  been  extracted.  A  radiograph  (Fig.  179)  shows  the  bone 
healthy.  The  simple  occlusal  filling  in  the  second  molar  penetrates  into 
the  pulp  chamber.  This  filling  was  removed,  and  the  semi-vital  pulp 
devitalized,  removed,  and  the  canals  filled.  The  result  was  an  immediate 
and  complete  recovery. 


Fig.  180  Fig.  181 

Fig.  180.  The  first  bicuspid  seems  to  hold  a  disto-occlusal  filling.  This  appearance  is  due 
to  a  slight  irregularity — a  slight  lapping  of  the  teeth.  The  filling  which  appears  to  be  in 
the  distal  of  the  first  bicuspid  is  in  the  mesial  of  the  second  bicuspid.  The  simple  oc- 
clusal filling  in  the  first  bicuspid  encroaches  into  the  pulp  chamber  slightly. 
Fig.  181.  The  same  as  Fig.  180  with  the  diseased  area  at  the  apex  of  the  first  bicuspid 
outlined,    to    enable    the    reader    to    see    it    better    in    Fig.    180. 


17.    Tn  Cases  of  teeth  with  Carge  metal  Tilling*  or  Shell  Crowns  Which  Do 
not  Respond  to  the  Cold  test,  to  Cearn  if  the  Canals  Arc  Tilled. 

Case :  Slight  swelling  and  pain  in  the  lower 
Tigs.  ISO  and  l$l.  bicuspid  and  first  molar  region.  The  patient  stated 
that  this  condition  had  occurred  and  recurred  many 
times  in  the  past  five  years.  At  no  time  had  the  swelling  been  great,  and 
the  pain  was  never  severe.  The  slight  swelling  and  an  annoying  pain 
would  last  for  a  few  days,  then  disappear  for  a  month  or  so.  There  was 
no  discharging  sinus.  The  first  molar  bore  a  gold  shell  crown,  the  second 
bicuspid  held  a  large  mesio-occluso-distal  amalgam  filling,  and  the  first 
bicuspid  had  a  small  filling  of  amalgam  in  the  occlusal  surface.  The 
three  teeth — the  first  molar  and  the  two  bicuspids — were  isolated  one  at  a 


1 82 


DENTAL   RADIOGRAPHY 


time  and  tested  with  cold  water.  The  patient  was  uncertain  as  to  whether 
he  received  any  sensation  when  the  cold  was  applied  to  the  shell-crowned 
molar,  but  thought  that  he  did.  The  second  bicuspid  responded  well,  and 
the  first  bicuspid  did  not  respond  at  all.  This  seemed  to  indicate  a  vital 
pulp  in  the  molar  and  second  bicuspid,  and  a  devitalized  one  in  the  first 
bicuspid.  But.  when  looking  for  a  dead  pulp,  one  would  naturally  sus- 
pect either  the  molar  with  the  shell  crown,  or  the  second  bicuspid  with 
the  large  filling,  instead  of  the  first  bicuspid  with  the  small  occlusal  filling 


Fig.    182.     The    roots    of    the    shell    crowned    first    molar    are    not    properly    filled.       Only    the 

upper  third   of  the   distal  canal   is   filled  and  the   mesial   canals   are  not   filled  at   all.      The   tooth 

was    sore    and    caused     annoying    neuralgic    pains. 


The  temperature  test  is  a  valuable  one,  but  it  cannot  be  depended  upon 
absolutely.  A  radiograph  (Fig.  180)  was  made.  It  shows  the  canals  of 
the  molar  and  second  bicuspid  unfilled.  The  tissues  at  the  apices  of  the 
roots  of  these  teeth  are  healthy,  which,  together  with  the  positive  reaction 
to  the  cold  tests  indicates  that  their  pulps  are  vital  and  healthy.  The 
simple  occlusal  filling  in  the  first  bicuspid  enters  the  pulp  chamber  slightly, 
the  canals  of  the  tooth  are  unfilled,  and  the  light  area  at  the  apex  of  the 
root  indicates  disease  (inflammation)  of  the  bone  in  that  region.  These 
things,  together  with  the  fact  that  the  tooth  did  not  react  to  the  cold  test, 
indicate  a  putrescent  pulp  in  the  first  bicuspid.  The  tooth  was  opened, 
and  the  diagnosis  confirmed. 

In  practice,  case  after  case  presents,  the  patient 

Tig.  IS2.  complaining  of  a  slight  soreness  or  annoying  pain  in 

the  region  of  a  shell-crowned  tooth,  or  a  tooth  with 

a  large  metal  lilling  in  it.     The  tooth  fails  to  respond  to  the  cold  test,  and 

lisped  that  the  canals  are  poorly  filled,  or  perhaps  not  filled  at  all. 
Are  we  justified  in  removing  the  crown  or  filling  to  examine  the  canals? 

re  the  radiograph  came  into  use  we  were,  but  not  to-day.  It  is  not 
fair  to  your  patient  nor  yourself  to  remove  a  canal  filling  unless  you  can 
improve  on  tin-  operation,     fig.   iSj  i-  a  radiograph  of  a  case  of  the 


THE  USES  OF  THE  RADIOGRAPH  IX  DENTISTRY     183 

class  just  alluded  to.  After  the  radiograph  was  made  I  had  no  hesitancy 
in  telling  the  patient  that  the  crown  should  be  removed  and  the  canals 
refilled.  There  were  only  about  four  millimeters  of  canal  filling  near  the 
mouth  of  the  distal  canal,  and  none  at  all  in  the  mesial  canals.  Before 
the  radiograph  was  made  I  was  unable  to  decide  whether  the  soreness 
and  neuralgia  were  caused  by  food  packing  down  between  the  first  and 
second  molar  (the  contact  point  is  bad)  or  improper  or  no  canal  filling. 


Fig.  183  Fig.  184 

Fig.    183.      Wire    just    penetrating    the    apical    foramen.       Showing    that    the    apical    sensitiveness 

is    not     due    to    an     unremoved,     undevitalized    remnant    of     pulpal     tissue. 

Fig.    184.     The    wire    in    the    canal    of    the    lateral    fails    to    reach    the    apex,     proving    that    the 

apical    sensitiveness   is   due   to   an    unremoved,   undevftalized    remnant   of   pulpal   tissue. 


1$.    to  Eearn  if  Apical  Sensitiveness  T$  Due  to  a  Carge  Apical  foramen  or  an 
Unremoved,  Undevitalized  Remnant  of  Pulp. 

In  the  treatment  of  teeth  we  often  pass  the 
TiflS.  l$3  and  IS4.  broach  into  the  canal  until  we  reach  what  we  know 
must  be  the  neighborhood  of  the  apex,  when  pain  is 
produced.  It  is  often  difficult  to  decide  whether  this  pain  is  due  to  some 
remaining  vital  pulp  tissue  in  the  canal,  or  the  penetration  of  the  broach 
through  the  apex.  Fig.  183  is  from  such  a  case.  The  wire  passing  to 
the  point  of  sensitiveness  goes  through  the  apical  foramen,  and  so  proves 
that  the  sensitiveness  is  not  due  to  unremoved,  undevitalized  pulp  tissue. 
In  Fig.  184  the  wire  reaching  the  point  of  sensitiveness  fails  to  reach  the 
apex,  proving  that  the  sensitiveness  is  caused  by  an  unremoved,  unde- 
vitalized remnant  of  pulp. 

Let  us  stop  to  consider  how  this  question  of  whether  or  not  we  are 
penetrating  the  apex  is  decided  when  radiographs  are  not  used.  We  pump 
phenol  or  some  other  obtundent  into  the  canal,  working  our  broach  farther 


IS4 


DENTAL   RADIOGRAPHY 


and  farther  until  we  strike  the  end  of  the  canal  ending  in  a  blind  alley,  or 
go  so  far  into  the  apical  tissues  we  know  that  no  tooth  root  could  be  as 
long  as  the  distance  we  are  penetrating.  The  use  of  the  radiograph  saves 
all  this  guesswork,  obviates  the  necessity  of  causing  considerable  pain  and 
is  a  time-saver. 

19.    Tn  Gases  of  Chronic  Pericementitis  (Came  tooth). 
A  putrescent  pulp  is  the  most  common  cause  for  pericementitis,  either 
chronic  or  acute.    Therefore,  when  the  affected  tooth  is  crowned  or  filled, 
as  it  almost  always  is  in  chronic  pericementitis,  radiographs  should  be 


Fig.  185  Fig.  186 

Fig.  185.  Gutta-percha  canal  filling  in  the  upper  lateral  passing  through  the  side  of  the  root 
to  the  distal.  The  canal  filling  also  penetrates  the  apical  foramen.  The  light  area  to  the 
mesial    along    the    apical    third    of    the    root    indicates    an    abscess.      The    mesial    surface    of    the 

root   is   roughened   in    the    region    of  the   abscess.      (Radiograph    by    Lewis   of    Chicago.) 

Fig.    186.     Canal    filling    penetrating    the    tissues    between    the    roots    of    the    lower    first    molar. 

(Radiograph    by    Kclls,    Jr.    of    New    Orleans.) 


made  to  learn  whether  the  canals  are  properly  filled,  and  treatment  may 
be  rendered  accordingly.  Fillings  and  crowns  without  contact  points,  or 
fillings  with  bad  gingival  margins,  or  crowns  which  do  not  fit  well  at  the 
cervix  or  penetrate  beneath  the  gum  margin  into  the  peridental  membrane, 
are  sometimes  the  causative  factors  in  chronic  pericementitis.  These 
things  may  be  detected  usually  without  the  aid  of  the  radiograph.  Often, 
however,  a  radiograph  will  demonstrate  the  fault  in  a  very  convincing 
manner.  Look  at  lig.  182,  for  example.  Observe  between  the  first  and 
second  molar  the  absence  of  a  contact  point,  the  bulging  of  the  crown 
band  into  the  interproximal  space,  and  the  slight  caries  of  the  alveolar 
process. 


The  illustration  does  no1  show  the  carious  process,  which,  however,  is  readilj 
diagnosed  in  the  original  film, 


THE  USES  OF  THE  RADIOGRAI'II  IN  DENTISTRY     185 

Figs.  185  and  186  demonstrate  lesions  that  might 
Tigs.  I$5  and  l$6.        he  responsible  for  chronic  pericementitis,  which  could 
not  be  detected  by  any  means  other  than  the  use  of 
the  radiograph. 


Fig.    187.     The   arrow   points   to  a   small    abscess   cavity    (the   light   area)    at   the   apex   of   a   lower 
central   incisor.      None   of   the   lower   anterior   teeth   had   cavities    in    them. 


Fig.  188  Fig.  189 

Fig.  188.  An  abscess  at  the  apex  of  an  upper  lateral  incisor.  This  abscess  pointed  directly 
over  the  dummy  central  incisor,  which  is  swung  in  on  a  post  collar  crown  on  the  lateral 
and  an  inlay   in  the   central   incisor.      The   central   does   not   show  clearly, — but   clearly   enough   to 

show   that   there   is    no   abscess   cavity    at   its   apex. 
Fig.    189.      The    same    as    Fig.    188    two    weeks    after    curettement    of    the    pus    sinus.      There    is 

some    deposition    of    new    bone. 


20.    Tn  Cases  of  Alveolar  Abscess  to  Determine  Which  tooth  is  Responsible 

for  the  Abscess. 

Case :    A  pus  sinus  opening  on  the  labial  between 

Tifl.  1$7.  tne    lower    central    incisors    near    their    apices.      All 

of   the   lower  anterior    teeth   sound   and   apparently 


DENTAL   RADIOGRAPHY 

healthy.  Fig.  187  shows  which  tooth  is  responsible  for  the  abscess. 
This  tooth  was  treated  and  the  abscess  cured.  The  light  area  to  which 
the  arrow  points,  about  the  apex  of  the  central,  represents  the  abscess 
cavity.  Acute  abscesses  cannot  always  be  shown  in  radiographs,  because 
there  may  not  be  sufficient  destruction  of  bony  tissue.  Chronic  abscesses, 
which  have  become  acute,  can,  of  course,  be  shown  radiographically. 


Fig.    190.     Abscess   at    apex   of    lower    second    bicuspid.      The    tooth    carries    a    gold    shell    crown. 

Canal     is    not     filled.       The     inferior     dental     canal    can    be    seen     plainly     in     this     radiograph — 

light    streak    between    two    dark    lines   along    the    lower    border    of    the    mandible. 


Case :  A  bridge  from  an  upper  lateral  incisor. 
Tifl$.  1$$  and  i$9.  with  a  post  collar  crown  to  a  central  with  an  inlay 
abutment,  restoring  a  lost  central  incisor :  a  sinus 
pointing  directly  above  the  dummy  central.  The  lateral  had  been  treated 
tor  an  abscess  two  years  previously.  The  abscess  had  yielded  to  the  treat- 
ment, the  canals  were  filled,  and  the  bridge  set.  At  the  time  when  the 
inlay  was  placed  in  the  central  it  was  vital.  A  radiograph  (Fig.  188)  was 
made  to  determine  whether  the  existing  sinus  was  due  to  a  recurrence  of 
the  abscess  of  the  lateral  or  death  of  the  pulp  and  abscess  of  the  central. 
The  radiograpli  shows  that  the  lateral  is  responsible.  As  the  canal  is 
fairly  well  filled  1  it  falls  short  of  the  apex  by  only  a  fraction  of  a  milli- 
meter), it  was  deemed  unnecessary  to  remove  the  crown.  An  incision 
made  on  the  labial  and  the  sinus  thoroughly  curetted,  cauterized  and 
filled  with  bismuth  subnitrate  paste.  The  extreme  apex  of  the  tooth  was 
curetted  away.  Fig.  189  is  of  the  same  case  two  weeks  after  the  opera- 
tion, at  which  time  there  were  no  symptoms  of  the  disease.  There  is  some 
deposit  of  new  bone — about  as  much  as  might  be  expected  in  two  weeks. 

Case  :    The  lower  first  and  second  molars  absent. 

Tifl.  190.  A  fistula  opening  directly  mesial  to  the  third  molar. 

The  third  molar  free  of  carious  cavities.     I  suspected 

a  piece  of  unremoved  root  of  the  missing  second  molar  to  be  responsible 

for  the  suppuration.     A  radiograph   (Fig.   [90)   was  made.     It  demon- 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     187 

strates  the  absence  of  any  piece  of  tooth  root,  and  shows  a  large  abscess 
at  the  apex  of  the  shell-crowned  second  bicuspid.  The  bicuspid  was 
opened  and  an  antiseptic  solution  forced  through  the  tooth  and  out  through 
the  fistulous  opening  in  front  of  the  third  molar. 

The  radiograph  does  not  show  the  fistulous  tract  leading  from  the 
bicuspid  backward  toward  the  third  molar.  The  probable  reason  for  this 
is  that  the  tract  passes  along  between  the  bone  and  periosteum.  There- 
fore, there  is  very  little  destruction  of  bony  tissue  throughout  its  course. 

Recently  the  following  case  presented :  Fistulous  opening  on  the 
labial  over  the  apex  of  a  perfectly  sound  upper  cuspid.  The  first  bicuspid 
apparently  healthy  save  for  a  small,  faulty,  amalgam  filling.  The  proxi- 
mating  lateral  shell  crowned.  I  suspected  the  crowned  lateral  to  be  the 
seat  of  the  trouble.  A  radiograph  was  made,  and  showed,  to  my  surprise, 
that  the  lateral  was  perfectly  healthy  and  its  canal  well  filled.  A  radio- 
graph of  the  first  bicuspid  was  made  and  showed  an  abscess  and  unfilled 
canals.  I  do  not  print  radiographs  of  this  case,  because  one  of  them,  the 
one  showing  the  abscess,  has  been  mislaid.  I  record  the  case  because  it  is 
one  the  like  of  which  a  person  may  run  across  any  day  in  practice. 

21.   in  Cases  of  Alveolar  Abscess  to  Determine  the  extent  of  tbe  Destruction  of 
tissue— Bony  and  tooth 

Case :   Shell-crowned,  lower  first  molar.  Chronic 
Tig.  191.  abscess  of  several  years'  standing.     The  crown  was 

removed,  and  the  tooth  treated.  The  flow  of  pus 
stopped.  The  canals  were  filled  and  the  crown  reset.  In  about  a  month 
there  was  a  recurrence  ot  pus  production.  A  radiograph  (Fig.  191)  was 
made,  and  shows  both  roots,  especially  the  mesial,  badly  absorbed.  The 
canal  fillings  penetrate  into  the  area  of  diseased  bone.  Considering  the 
clinical  appearance  and  history  of  the  case,  and  the  great  amount  of  tooth 
structure  destroyed,  apicoectomy  was  not  indicated.  I  therefore  ad- 
vised extraction.  A  most  peculiar  fact  in  this  case  is  the  great  destruc- 
tion of  tooth  structure,  and  the  comparatively  slight  destruction  of 
the  alveolar  bone ;  the  reverse  of  what  is  usually  found.  Not  only  is 
there  little  destruction  of  bone,  but  bony  tissue  seems  actually  to  have 
filled  in  the  space  formerly  occupied  by  the  tooth  roots. 

One  of  the  most  perfectly  circumscribed  alveo- 

Tifl.  192.  lar  abscesses  I  have  ever  seen.     The  abscess  occurs 

at  the  apices  of  the  roots  of  the  upper  first  bicuspid. 

Notice  how  the  two  roots  extend  into  the  abscess  cavity.     The  very  light 

shade  of  bone  to  the  distal  of  the  bicuspid  is  diseased,  somewhat  carious, 

but  will  regain  normal  vitality  in  all  probability  when  thorough  drainage 


[88  DEXTAL   RADIOGRAPHY 

of  the  abscess  is  obtained.     A  case  like  this  should  yield  to  treatment 
without  extraction.     Perhaps  apicoectomy  would  be  necessary. 

A  very  large  abscess  involving  the  upper  central 

Tig.  193.  and  lateral  incisors  of  one  side.    I  am  unable  to  learn 

what  treatment  was  given  in  this  case.     Basing  my 

judgment  on  the  appearance  of  the  radiograph,  without  any  clinical  knowi- 


ng.  191  Fig.   192 

Fig.    191.      Both    roots   of   the    shell-crowned,    lower,    first    molar    badly    absorbed,    especially    the 

mesial.     Canal  fillings  extend  beyond  the  ends  of  the  roots. 
Fig.  192.     An  almost  perfectly  circumscribed  abscess  about  the  roots  of  an  upper  first  bicuspid. 
Note  how  the  roots  extend  into  the  abscess  cavity.      (Radiograph  by   Blum,  of  New  York   City.) 

edge  of  the  case,  I  would  say  that  the  lateral  should  be  extracted,  and 
the  opening  so  made  into  the  abscess  cavity  enlarged  to  the  distal  to  such 
an  extent  as  to  permit  a  thorough  curettement  of  the  suppurating  sinus. 
(This  would  necessitate  removal  of  the  bridge  from  first  bicuspid  to 
cuspid.)  Or,  perhaps  an  opening  sufficiently  large  to  permit  thorough 
curettement  and  drainage  could  be  made  through  the  external  alveolar 
plate  and  the  lateral  conserved.  At  any  rate,  knowing  that  the  opening 
into  a  pus  sinus  to  drain  and  curette  it  thoroughly  must  vary  directly 
according  to  the  size  of  the  sinus,  we  can  see  that,  in  this  case,  the  open- 
ing must  be  quite  large.  Such  an  abscess  could  not  be  drained  sufficiently 
well  through  pulp  canals. 

Fig.    194  shows  how  utterly    futile   it   would   be 

Tig.  194.  to  attempt  to  treat,  and  retain  in  the  mouth,  such  a 

tooth  as  is  shown  in  the  radiograph.  Such  a  condi- 
tion could  not  have  been  diagnosed  by  means  other  than  the  use  of  the 
X-rays.  The  small,  dark  streak  through  the  tooth  is  a  wire.  Note  the 
great  destruction  of  the  tooth  root  and  the  carious  condition  of  the  sur- 
rounding bone. 

Case:    Sinus  opening  near  the  apex  of  an  upper 

Tig.  195.  central  incisor.    The  tooth  did  not  yield  to  treatment. 

It  was  treated  on  the  assumption  that  there  was  con- 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     189 

siderable  destruction  of  bone,  and  powerful  stimulating  corrosives,  like 
phenolsulphonic  acid,  were  forced  beyond  the  apex.  That  such  treatment 
was  improper  is  demonstrated  by  the  radiograph  (Fig.  195),  which  shows 
that  there  is  very  little  bone  destruction.  Accordingly  the  more  radical 
line  of  treatment  was  dropped,  the  sinus  injected  with  bismuth  subnitrate 
paste,  a  mild  antiseptic  sealed  in  the  canal,  and  the  tooth  allowed  to  rest 
unmolested  for  ten  days,  at  the  end  of  which  time  all  pathological  symp- 
toms had  disappeared. 


Fig.    193 


194 


Fig.    195 

Fig.    193.      Very    large    abscess   involving   the    lateral    and    central,    and    extending   almost    to    the 

apex  of  the  first   bicuspid.      (Radiograph  by    Peabody,   of   South   Orange,   N.   J.) 

Fig.   194.     Absorption   of  the  root  and  surrounding  bony  tissue.     A  wire  is  seen   passing  into  the 

canal.      (Radiograph  by  Blum,   of  New   York   City.) 

Fig.   19o.     A  very  small  abscess  cavity  at  the  apex  of  the  central  with  the  wire  in  it. 


22.    Tn  Cases  of  Alveolar  Abscess  to  Eeam  fiow  many  teeth  are  Involved. 

I  recall  having  treated  an  abscessed  central  in- 
Tifl.  196.  cisor  for  a  month  without  effecting  a  cure,  or  even 

much  improvement.  The  apical  foramen  was  well 
opened,  and  antiseptic  and  stimulant  washes  could  easily  be  forced 
through  the  tooth  and  out  through  the  fistulous  opening  on  the  gum.  as- 
suring me  that  I  had  good  drainage.  The  lateral  at  the  side  of  the  cen- 
tral did  not  respond  to  the  cold  test,  but  neither  did  any  other  tooth  in 
the  patient's  mouth.  Despite  the  fact  that  it  was  a  sound  tooth,  I  opened 
into  the  lateral,  removed  the  pulp,  which,  while  devitalized,  was  not  badly 
putrescent,  enlarged  the  apical  foramen,  and  found  that  washes  forced 
into  the  lateral  came  out  both  the  fistula  and  central.  While  the  case  is 
not  the  same,  the  conditions  which  I  then  combated  in  the  dark  ( I  did 
not  use  the  X-rays  in  my  practice  at  this  time),  are  shown  in  Fig.  196. 
An  abscess,  involving  both  central  and  lateral,  is  shown  bv  the  light  area 


190 


DEXTAL   RADIOGRAPHY 


about  and  above  their  apices.    In  this  case  the  canal  of  the  central  is  only 
partially  filled,  and  the  lateral  canal  not  filled  at  all. 

An  abscess  pointing  in  the  palate.    A  radiograph 

fig.  197.  <  Fig.  197)  was  made  to  determine  which  tooth  was 

responsible.      The   central,    lateral,    cuspid   and    first 

bicuspid  were  suspected.     The  radiograph  shows  that  all  of  these  teeth 


•  ■■  *" 

H 

Fig.    190  Fig.    197 

96.     Abscess  involving  the  central  and  lateral  incisors.     The  canal  of  the  central  is  partially 
rilled.      (Radiograph  by  Lewis,  of  Chicago.) 
Fig.    197.     A   large  abscess  involving  the  central,  lateral  and  cuspid. 

except  the  first  bicuspid — i.e.,  the  central,  lateral  and  cuspid — are  in- 
volved. The  abscess  was  treated  through  all  three  teeth,  but  did  not 
yield  to  this  treatment.  It  was  deemed  necessary  to  curette  the  sinus.  An 
opening  through  which  the  sinus  could  be  curetted  was  made  by  extract- 
ing the  lateral  root.  Perhaps  there  are  those  who  will  condemn  my 
surgery,  saying  the  tooth  should  have  been  conserved  and  the  opening 
made  into  the  sinus  through  the  external  alveolar  plate.  My  reason  for 
extracting  the  tooth  root  is  that  I  was  quite  uncertain  as  to  the  exact 
labial  palatal  location  of  the  sinus — recollect  the  abscess  pointed  on  the 
palate. 

23.    Tn  Cases  of  Abscess  of  multirooted  teeth,  to  nearn  at  the  flpex  of  Ulhich  Root 

the  Abscess  exists. 

This  radiograph  shows  an  abscess  at  the  apex 
Tig.  19$.  of  the   mesial   root   of  a  shell-crowned,  lower  first 

molar.    The  canals  of  the  tooth  are  not  filled.    With- 
out this  picture  to  guide  US  a  great   deal  of  time  and  energy  might  be 
ed  in  opening  and  enlarging  the  apical   foramen  of  the  distal  canal, 
which  is  worse  than  unnecessary.     Knowing  thai  the  abscess  is  at  the 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     [91 

apex  of  the  mesial  root,  we  should  try  to  obtain  drainage  by  opening  one 
or  both  of  its  apical  foramina.  This  is  not  always  possible,  despite  loud 
and  angry  protestations  to  the  contrary.  If,  after  earnest,  conscientious, 
and  prolonged  effort  the  mesial  foramina  cannot  be  enlarged,  obtain 
drainage  by  opening  through  the  buccal  alveolar  plate,  directing  the  bur 
towards  the  mesial  root.  _^^_^^^^^___^^_^^^^^^^ 


^|^g| 


Fig.   198  Fig.    199 

Fig.  198.      Abscess  at   the   apex   of   the   mesial   root  of  the  shell-crowned,   lower,   first   molar.      The 

canals  of  the  tooth   are   not  filled.      (Radiograph   by   Blum,    of   New   York   City.) 
Fig.   199.     Large  abscess   involving  both   roots  of   the  lower   first   molar  and   probably   both   roots 
of   the    second    molar.      The    distal    canal    of    the    first    molar    is    partially    filled.       (Radiograph    by 

Ream,  of   Chicago.) 

A  large  abscess  involving  both  roots  of  the  lower 
Tig.  iw.  first  molar  and  probably  both  roots  of  the   second 

molar.  Without  a  history  of  the  case  to  guide  me, 
I  should  say,  judging  from  the  appearance  of  the  radiograph,  that  both 
the  first  and  second  molar  need  treatment.  The  apical  foramina  of  the 
first  molar  should  be  opened,  and  good  drainage  through  the  alveolar 
plate  established  also.  Enlargement  of  the  apical  foramina  of  the  second 
molar  would  probably  be  unnecessary. 

24.  Tn  eases  of  Abscess  of  Crowned  teeth  to  Eearn  if  the  Canals  are  Properly  Tilled. 

It  is  a  common  occurrence  in  practice  to  have  a  patient  present  with 
a  pus  sinus,  discharging  in  the  region  of  the  apex  of  a  tooth  carrying  a 
crown.  If  the  canals  of  the  tooth  are  properly  filled,  we  should  treat  the 
sinus  through  the  external  alveolar  plate ;  if  the  canals  are  not  properly 
filled,  then  the  crown  should  be  removed  and  the  case  treated  through 
the  tooth — perhaps  through  the  external  alveolar  plate  also,  depending 
on  the  extent  of  the  destruction  of  tissue.  Whether  or  not  the  crown 
should  be  removed  is  determined  by  the  use  of  the  radiograph. 

See  Fig.  188.  This  radiograph  shows  that  it  is  quite  unnecessary  to 
remove  the  post-collar  crown  (an  abutment  of  a  bridge)  from  the  ab- 
scessed lateral,  for  the  canal  is  well  filled.     As  formerlv  recorded,  the 


192 


DENTAL   RAD10GRA1  HY 


treatment  of  this  case  was  chiefly  surgical,  through  the  external  alveolar 
plate,  and  was  effective. 

In  the  third  edition  of  his  Modern  Dental  Ma- 
Tig.  200.  tcria  Medico,  Pharmacology  and  Therapeutics,  Dr. 

Buckley  prints  Fig.  200,  and  the  following  descrip- 
tion :     Fig.  200  '"shows  the  involvement  of  the  upper  central  and  lateral 


Fig.    201 


Fig.    201 


Fig.  200.  Abscess  involving  the  upper  central  and  lateral  incisors.  There  was  but  one  fistulous 
opening  on  the  labial.  Since  the  canals  of  central  and  lateral  are  both  properly  filled  the 
treatment  should  consist  simply  of  curettement  of  the  affected  area,  which,  of  course,  does  not 
necessitate    the    removal    of   the    post-porcelain    crowns    from    the    teeth.      (Radiograph    by    Ream, 

of   Chicago.) 

Fig.    201.      Dr.    Rhein    says    of    Fig.    201:    "This    is    a    typical    case    of    chronic    alveolar    abscess, 

which    for   years    had    been    erroneously    treated    for    pyorrhea." 


Fig.  2H-.'.     Alveolai  abscess  wrongly  diagnosed  as  pyorrhea.     (Radiograph  bj    Rhein,  "i   New  York.) 

incisors  in  an  abscess.  Both  teeth  carried  perfectly  adjusted  porcelain 
cr<iwn>.     The  skiagraph  not  only  shows  the  involvemenl  of  both  teethi 

but  also  that  the  roots  are  properly  filled.  The  treatment  here  is  purely 
surgical,  and  means  the  curettement  of  the  affected  area."  Had  the 
radiograph  not  been  used  the  operator  would,  in  all  probability,  have 
made  the  laborious  and  foolish  mistake  of  removing  the  crowns  on  the 
assumption  that  tlie  canals  were  not  properly  filled. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     193 

25.    Hs  an  Hid  in  Differential  Diagnosis  Between  Chronic  Alveolar  Abscess  and 
Pyorrhea  Alveolaris. 

When  a  chronic  alveolar  abscess  discharges  about  the  neck  of  a  tooth 
the  case  so  closely  simulates  calcic  pyorrhea  alveolaris  that,  without  using 
the  radiograph  or  opening  into  the  affected  tooth,  the  operator  cannot 
make  a  definite  diagnosis. 


Fig.   203  Fig.    204 

Fig.   203.     Absorption  of  the   bone   around   the   molar   due   to   pyorrhea   alveolaris.      The   tooth   ha* 

no  bony   attachment   at  all.      (Radiograph   by   Ream,   of  Chicago.) 
Fig.  204.     Absorption  of  the  bony  tissue  due  to  pyorrhea  alveolaris.     The  distortion   (elongation) 
enables  us  to  observe  clearly  little  spiculae  of  diseased  bone.     The  central  has  no  bony  attachment, 

except  at  the  extreme   apex. 

This  is  a  case  from  the  practice  of  Dr.   M.  L. 
Tig.  201.  Rhein,  of  New  York  City.     Dr.  Rhein  says:     "This 

is  a  typical  example  of  a  chronic  alveolar  abscess, 
which  for  years  had  been  erroneously  treated  for  pyorrhea." 

Fig.     202    represents    another    case    from    the 

Tig.  202.  practice    of    Dr.    Rhein,    which    had    been    wrongly 

diagnosticated  as  pyorrhea.     The  lateral  incisor  was 

supposed   to  be  affected   by   pyorrhea,   but    after   making  a   radiograph. 

Fig.  202    it  was  seen  that  the  real  trouble  was  an  apical   abscess,   the 

infection  arising  from  the  death  of  the  pulp. 

26.    Co  Observe  Destruction  of  tissue  Due  to  Pyorrhea  Alveolaris. 

Other  factors  being  equal,  our  chances  of  curing 
Tig.  203.  pyorrhea  alveolaris  vary  inversely  according  to  the 

amount  of  destruction  of  alveolar  process  surround- 
ing the  affected  teeth.  Fig.  203  demonstrates  the  futility  of  treating 
and  attempting  to  conserve  the  molar  tooth.  All  of  the  bone  immediately 
surrounding  the  tooth  is  destroyed. 


194 


DENTAL   RADIOGRAPHY 


A  central  incisor  affected  with  pyorrhea.     The 

fig.  204.  tooth  has  no  bony  attachment  except  at  its  extreme 

apex.     Extraction  is  indicated.     The  distortion — the 

elongation — in  this  picture  enables  us  to  observe  the  diseased  bone  to  the 


Fig.    205 


Fig    200 


Fig.   205.      The   distal   root   of  the   first   molar   has   practically   no   bony   attachment   and   is   badly 
roughened.     It  was  extracted.     The  arrow  points  to  an  absorbed  notch  in  the  distal  root. 
.      .    '..      The    arrow    points   to   bit    of   calculus    on    t lie    distal    of    a    second    bicuspid.      The    lighl 
area   above   the   calculus   denotes   the   destruction    of   bone   and    represents   a   pyorrhea   pocket. 


left  of  the  central  unusually  well.  In  the  negative  now  before  me  I  can 
see  clearly  the  soft  tissue  between  the  centrals.  Looking  to  the  mesial  and 
distal,  I  can  distinguish  also  the  enamel  of  the  central.  The  lingual 
enamel  in  the  incisal  region  has  been  worn  away ;  hence  the  lighter 
shadow  of  the  tooth  in  this  region. 

A    lower    first    molar    affected    with    pyorrhea. 
Tig.  20S.  The  distal  root  appears  roughened,  due  to  a  necrotic 

condition  of  its  surface  and  the  presence  of  calculus 
on  it.  It  has  no  attachment  to  bone  except  at  its  extreme  apex.  The 
alveolar  process  to  the  mesial  of  the  mesial  root  is  comparatively  healthy. 
The  tissues  to  the  distal  of  the  mesial  root  are  not  as  healthy  as  those  to- 
the  mesial,  but  not  so  badly  diseased  that  they  cannot  regain  a  healthy 
vitality.  The  treatment  of  this  case  should  be  begun  with  extraction  of 
the  distal  root.  This  was  done,  and  the  mesial  root  successfully  con- 
served. 

A   pyorrhea  pocket  on  the  distal  of  an   upper 
Tifl.  20t>.  second  bicuspid.     There  is  but  slight  destruction  of 

bone.     The  most  remarkable  thing  about  this  picture 
is  that  it  shows  a  bit  of  calculus  on  the  distal  of  the  second  bicuspid. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     195 

27.    Tn  Cases  of  Pericemental  Abscess. 

"Pericemental  abscesses  have  been  described  by  numerous  writers,  one 
of  the  best  papers  on  the  subject  being  that  by  Dr.  E.  C.  Kirk,  published 
in  the  Dental  Cosmos  for  November,  1900.  There  are  various  views  as 
to  the  etiology  of  this  condition,  but  the  main  point  of  interest  lies  in  the 
fact  that  pericemental  abscess  occurs  on  the  root  of  a  tooth  in  which  the 


Fig.   207  Fig.   208 

Fig.    207.      Pericemental    abscess   at   apex   of   upper   cuspid.      The   crowned   first   bicuspid   was   sus- 
pected,  but   the   radiograph   shows   an   abscess  at  apex   of   the   cuspid,    which   was   sound   and   alive. 
Fig.  208.     The  light  area  to  which  the  arrow  points  is  a  pericemental  abscess. 

pulp  is  still  alive,  a  fact  which  renders  a  true  diagnosis  sometimes  quite 
complex.  For  example,  a  patient  might  present  with  a  well  defined  fis- 
tula appearing  between  the  roots  of  two  teeth,  one  of  which  may  be 
perfectly  sound,  whereas  the  other  might  be  just  as  certainly  pulpless.  It 
would  be  quite  reasonable  for  the  operator  to  conclude  that  an  abscess 
originated  from  infection  coming  from  the  root  of  the  pulpless  tooth,  and 
to  treat  such  a  tooth,  it  might  be  necessary  to  remove  important  and  well 
constructed  work,  such  as  an  inlay  or  a  bridge  abutment.  A  radiograph, 
however,  will  disclose  that  the  abscess  involves  the  pericementum  of  the 
living  tooth,  and  thus  the  dentist  would  be  saved  the  mortification  of  un- 
necessarily destroying  the  inlay  or  abutment  attached  to  the  pulpless  tooth, 
and  the  patient  would  be  saved  the  annoyance  and  expense  involved  in 
such  a  misconstruction  of  symptoms. 

"From  the  practice  of  Dr.  M.  L.  Rhein  is  a  case 
Tifl.  207.  °f    tnis    character.      The    bicuspid    is    crowned    and 

might  have  been  suspected  as  the  cause  of  the  ab- 
scess, especially  as  in  the  radiograph  only  one  root  canal  filling  is  seen, 
but  the  history  of  the  case  made  this  impossible.     The  tooth  was  treated 


i,,..  DENTAL   RADIOGRAPHY 

twelve  years  ago  for  an  abscess,  and  both  canals  were  perfectly  filled, 
as  can  be  seen  in  other  radiographs  of  the  case  in  the  possession  of  Dr. 
Rhein.  these  radiographs  being  taken  at  a  slightly  different  angle.  The 
tooth  having  remained  perfectly  comfortable  during  all  of  these  years. 
the  well  defined  abscess  disclosed  at  the  apex  of  the  cuspid  tooth  was 
diagnosed  as  a  pericemental  abscess.  The  tooth  in  question  was  abso- 
lutely sound,  having  no  tilling  or  cavity  of  any  kind,  and  when  opened  the 
pulp  was  found  to  be  alive.  Also  there  was  no  taint  of  pyorrhea  in  this 
mouth.  This  diagnosis  was  confirmed  by  the  fact  that  the  removal  of 
the  pulp  from  the  cuspid  and  subsequent  treatment  through  the  canal 
effected  a  perfect  cure.*" 

Case :     A  sinus  discharging  near  the  apex  of  an 
Tig.  20$.  upper  cuspid.     The  cuspid  had  no  carious  cavity  in 

its  crown,  and  responded  to  the  cold  test.  A  radio- 
graph i  Fig.  208)  was  made  and  shows  a  pericemental  abscess  on  the 
distal  side  near  the  apex  of  the  cuspid,  but  not  involving  the  apex,  and 
hence   was   not   involving  the   pulp. 

It  would  have  been  a  mistake  to  remove  the  pulp  from  the  cuspid 
because  it  was  not  involved.  An  incision  was  made  through  the  external 
alveolar  plate,  the  pus  sinus  was  thoroughly  curetted  and  then  filled  with 
bismuth  paste.     The  result  was  a  prompt  and  complete  cure. 

Buckley,  in  his  last  edition  of  his  Modern  Dental  Materia  Mediea, 
Pharmacology  and  Therapeutics,  prints  a  radiograph  similar  to  Fig.  208. 
Before  the  radiograph  was  used,  in  the  case  reported  by  Dr.  Buckley,  the 
pericemental  abscess  was  diagnosed  as  an  alveolar  abscess,  due  to  a  dead 
pulp.  The  tooth  thought  to  contain  a  dead  pulp  was  opened,  and  a  vital 
pulp  found.  The  operators  who  handled  the  case  experienced  a  great  deal 
of  difficulty  in  removing  the  pulp,  nitrous  oxygen  anesthesia  being  re- 
sorted to  finally  to  accomplish  it.  After  removal  of  the  pulp  "the  tooth  (a 
central  incisor)  became  dark  blue  in  color."  In  concluding  the  report  of 
this  case,  Dr.  Buckley  says:  "The  patient  in  this  instance  was  a  lady. 
and  when  we  recall  that  the  tooth  involved  was  an  anterior  one.  the 
»f  the  mistaken  diagnosis  becomes  all  the  more  apparent." 

Compared  to  die  occurrence  of  alveolar  abscesses,  as  caused  by  in- 
fection   from  dead  pulps,  pericemental   abscesses  are  rare. 

2$.  Tn  eases  of  Persistent  Suppuration  Which  Do  not  Yield  to  the  Usual  treatment. 

Case:    Girl  eighteen  years  old.  had  had  a  lower 

j\q    209.  '""1  molar  extracted  two  months  previous  to  the 

time  when   she  presented  to  me   for  treatment.     The 

socket    from    which    the    second    molar   had   been   extracted    was   an   open 

Dr.  R.  Ottolengui. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     197 

suppurating  sure.  The  patient  was  poor,  and,  wishing  to  spare  her  the 
expense  of  having  a  radiograph  made,  a  diagnosis  was  made  to  the  best 
of  my  ability  by  other  means — by  symptoms  and  instrumental  examina- 
tion. The  diagnosis  was  infection  by  some  particularly  virulent  pyo- 
genic organisms  and  a  slight  caries  of  the  bone.  I  was  unable  to  locate 
any  unremoved  piece  of  tooth  root.  The  socket  was  vigorously  curetted 
and  cauterized  with  phenolsulphonic  acid,  a  mouth-wash  prescribed,  and 
the  patient  instructed  to  return  in  three  days.    When  next  seen  there  was 


Fig,    809 


Fig.   210 


Fig.    209.      An    unerupted    third    molar   which    caused   sufficient    irritation    to   sustain    a    suppurating 

wound  from   where  a  second  molar  was   extracted. 

Fig.    210.      A   case   of   persistent    suppuration    of   several    years'    standing.      The    radiograph    shows 

the    cause — an    impacted,    malposed    upper    cuspid.      (Radiograph    by    Lewis,    of    Chicago.) 


but  slight  improvement  in  the  objective  symptoms,  and  the  patient  re- 
ported that  there  had  been  no  abatement  in  pain  and  soreness.  The  lesion 
was  washed  thoroughly  with  an  antiseptic  solution,  and  the  patient  in- 
structed to  return  in  three  days.  When  seen  again  there  was  no  improve- 
ment over  what  had  existed  before  the  operation.  Wishing  to  get  a  more 
complete  and  reliable  history  of  the  case,  I  consulted  with  the  patient's 
physician.  He  had  treated  the  oral  lesion  before  the  case  came  to  me, 
and  was  of  the  opinion  that  it  was  tubercular.  He  suggested  the  tuber- 
culin treatment.  A  radiograph  (Fig.  209)  was  made  to  make  sure  that 
there  was  not  a  piece  of  the  second  molar  still  in  the  jaw.  As  can  be 
seen,  there  is  no  piece  of  tooth  root  present,  but  what  we  do  see  is  an 
erupting  third  molar.  Perhaps  I  should  have  thought  of  the  third  molar 
as  a  cause  for  the  trouble.  But  I  did  not  until  the  radiograph  was  before 
me.  Believing  this  tooth,  in  its  effort  to  erupt,  to  be  responsible  for  a 
slight  irritation  and  the  consequent  suppuration,  the  soft  tissues  and  the 


198 


DEXTAL   RADIOGRAPHY 


bone  covering  it  were  dissected  away.  The  result  was  immediate  im- 
provement. I  regret  that  I  cannot  definitely  report  a  complete  recovery, 
but  I  am  sure  it  occurred.  The  patient  left  the  city  about  a  week  after 
the  last  operation,  and  I  have  not  seen  nor  heard  from  her  since. 

I  have  already  referred  to  a  case  of  persistent 
fig.  210.  suppuration,  reported  by  Dr.  T.  W.  Brophy,  which 

did  not  yield  to  treatment  until  a  radiograph  dis- 
closed the  presence  of  a  supernumerary  tooth,  and  it  was  removed.  In 
answer  to  a  letter  of  mine,  asking  for  a  radiograph  of  the  case,  Dr.  Brophy 


Fig.   211  Fig.   212 

Fig.  211.  Abscess  at  the  apex  of  the  shell-crowned,  second  bicuspid.  It  is  very  difficult  to 
observe  either  the  abscess  or  the  unfilled  canal  in  the  bicuspid  in  the  print,  though  both  show 
clearly  in  the  negative.     The  arrow  A  points  to  the  abscess  at  the  apex  of  the  tooth.     The  arrow 

B  points  to  an  abscess  on  the  side  of  the  root,  caused  by  the  ill-fitting  shell-crown. 

Fig.  212.     Same  case  as  Fig.  211.     The  dark  shadow  is  bismuth  paste.     It  passes  from  the  apex 

of  the  upper  second  bicuspid  downward  and  towards  the  second  molar. 


informed  me  that  it  could  not  be  found,  and  enclosed  Fig.  210,  saying  it 
was  a  similar  case,  i.e.,  a  case  of  persistent  suppuration,  which  did  not 
yield  to  treatment  until  the  radiograph  showed  the  exciting  cause,  and  it 
was  removed.  The  history  of  the  case,  illustrated  in  Fig.  210,  is  about 
as  follows :  The  upper  lateral  became  abscessed.  It  was  treated,  and  the 
canals  rilled.  Pus  continued  to  flow  from  a  fistulous  opening  on  the  labial. 
The  abscess  was  treated  through  the  alveolar  plate,  but  without  success. 
A  radiograph  was  made.  I  quote  Dr.  Brophy.  "It  (the  radiograph) 
exhibits  a  cavity  in  the  bone,  absorption  of  the  apex  of  the  root  of  the 
lateral,  as  well  as  the  apex  of  the  root  of  the  adjacent  central  tooth. 
Above  is  an  impacted  cuspid  lying  in  a  nearly  horizontal  position.  To 
cure  a  case  of  this  character  calls  for  most  careful  study,  deliberation 
and  action.  The  course  to  pursue  is  largely  dependent  upon  the  condition 
of  the  other  teeth  forming  the  upper  denture.  In  a  young  person,  the 
removal  of  the  lateral  incisor  root,  which  is  crownless  and  diseased,  and 
the  gradual  moving  downward  into  its  place  of  the  cuspid  would  be  the 
desirable  procedure.     If  the  patient  is  in  middle  life,  and  the  teeth 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     199 

badly  diseased  and  loose,  as  the  teeth  here  represented  are,  I  would  rec- 
ommend the  removal  of  the  diseased  teeth,  diseased  bone,  and  impacted 
tooth.  The  history  of  this  case,  with  suppuration  extending  over  a  period 
of  several  years,  so  beautifully  and  clearly  illustrated  by  the  use  of  the 
Roentgen  photograph,  impresses  us  with  the  inestimable  value  of  this 
means  of  reaching  a  diagnosis." 

29.    to  Observe  the  Course  of  the  fistulous  tract. 

Dr.  Emil  Beck,  of  Chicago,  was  the  first  to  use  bismuth  paste*  in 
radiography.  The  paste  is  opaque  to  X-rays.  Thus  Dr.  Beck  would 
inject  a  fistula  and  abscess  cavity,  then,  with  the  paste  injected,  make  a 


Fig.  213.      Bismuth   paste  injected  into  fistulous  opening  just  above  the  first  bicuspid  dummy  and 
nearly   filling   a   very   large  abscess   cavity.      (Radiograph   by    Ream,   of   Chicago.) 


radiograph.  Deep  shadows  would  be  cast  onto  the  film  or  plate  by  the 
subnitrate  of  bismuth,  showing  distinctly  the  course  of  the  fistula  and  the 
extent  of  the  abscess  cavity. 

The  curative  property  of  bismuth  paste  was  discovered  truly  by  acci- 
dent. After  using  the  paste  to  enable  him  to  make  better  radiographs, 
Dr.  Beck  noticed  that  some  bad  pus  cases  recovered. 

"Cargentos,"  a  colloidal  silver  oxid,  made  by  Mulford  &  Company, 
can  be  used  as  bismuth  paste  is  used,  for  either  radiographic  purposes  or 
as  a  remedy. 

When  the  use  "to  observe  the  course  of  a  fistulous  tract"  suggested 
itself  to  me,  I  had  in  mind  a  case  which  I  treated  some  years  ago.  It  was 
a  case  in  which  a  fistula  pointed  externally  at  the  symphysis.  Without 
going  into  a  detailed  history  of  the  case,  let  it  suffice  to  say  that  a  sound 
and  not  very  badly  impacted  lower  third  molar  was  finally  extracted  and 
the  case  recovered.  Probing  to  the  seat  of  the  trouble  was  impossible, 
but  had  the  fistula  been  injected  with  bismuth  paste  and  a  radiograph 
made,  the  connection  between  the  third  molar  and  the  fistulous  opening 

*Bismuth  subnitrate,  vaseline,  paraffine  and  white  wax. 


200  DENTAL   RADIOGRAPHY 

at  the  symphysis  would  have  been  clearly  shown.  1  regret  that  I  have 
not  been  able  to  obtain  a  radiograph  of  such  a  case.  I  have  not,  however, 
and  must,  therefore,  content  myself  with  a  report  of  the  only  case  I  have 
in  which  bismuth  paste  was  used  to  trace  a  fistulous  tract. 

Case :  A  fistulous  opening  on  the  buccal  near 
Tigs,  211  and  212.  the  apex  of  an  upper  second  bicuspid  ;  the  first  molar 
missing.  Another  fistulous  opening  on  the  buccal 
just  above  the  gingival  line  of  the  second  molar.  A  probe  entering  the 
fistula  above  the  bicuspid  led  to  its  apex.  A  probe  entering  the  fistula  of 
the  molar  seemed  to  lead  to  the  bifurcation  of  the  roots  of  the  molar. 
Having  at  a  previous  date  treated  the  molar,  and  so  knowing  the  condi- 
tion of  the  canals,  I  was  reluctant  to  believe  that  the  tooth  was  abscessed. 


Fig.   214  Fig.   215 

Fig.   214.      Before  apicoectomy.      Notice   the   considerable  canal   filling   forced   through   the   apical 

foramen.      (Radiograph  by  Blum,  of  New  York  City.) 
Fig.  215.     Same  case  as  Fig.  214.     After  apicoectomy.     (Radiograph  by  Ilium,  of  New  York  City.) 

I  entertained  the  belief  thai  both  fistulous  openings  led  to  an  abscess  at 
the  apex  of  the  bicuspid,  but  1  could  not  verify  this  belief  by  probing.  A 
radiograph  (Fig.  21 1)  shows  the  canals  unfilled,  and  an  abscess  at  the 
apex  of  the  bicuspid.  It  shows  also  that  there  is  no  abscess  at  the  apex 
of  the  molar  roots.  But  it  does  not  show  a  fistula  leading  from  the  bi- 
cuspid to  the  molar.  The  shell-crown  on  the  bicuspid  was  removed  and 
phenolsulphonic  acid  pumped  through  the  tooth  and  out  of  the  fistula 
over  the  bicuspid,  but  the  acid  could  not  be  forced  through  the  bicuspid 
and  out  at  the  opening  over  the  molar.  The  tooth  and  both  fistulous 
openings  were  injected  with  bismuth  paste  and  a  radiograph  made.  (Fig. 
212.1  I  was  then  able  to  see  that,  as  I  bad  suspected,  the  seat  of  the 
trouble  was  at  the  apex  of  the  bicuspid.  The  molar  did  not  need  treat- 
I  be  phenolsulphonic  acid  could  not  be  forced  through  the  bicus- 
pid and  out  at  the  molar  fistulous  opening,  because  it  traveled  the  path  of 
least  resistance  out  the  nearer  opening.     The  fistulous  tract  could  not  be 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     201 

seen  without  injection  with  bismuth  paste,  because  there  was  so  little 
bone  destruction.  Throughout  most  of  its  course  the  fistula  traveled  be- 
tween bone  and  periosteum. 

A  large  abscess  arising  at  the  apex  of  the  sec- 
Tig.  213.  oncl  bicuspid,  and  discharging  above  the  artificial  first 
bicuspid.     Bismuth  paste  injected  into  the  fistulous 
tract.     Perhaps  the  cuspid  is  involved  also.     It  should  be  tested  for  vital- 
ity of  its  pulp. 


Fig.    216 


Fig.   217 


Fig.    218 


Fig.   216.      The  apex    of   the   lateral   was   cut    off,    then   lost.      The    radiograph    shows   its    location, 

so  aiding  materially  in   its  removal.      (Radiograph  by   Ream,   of   Chicago.) 
Fig.   217.     A  chronic  abscess  at  the  apex  of  an   upper   central   incisor.     The  tooth   carries   a  post- 
porcelain  crown  and  the  canal  is  filled  almost  to  the  apex.      (Radiograph   by   Lewis,   of  Chicago.) 
Fig.    21S.      The   same  as  Fig.   217   four   days   after  the   amputation   of   the   apex    of  the   central   and 
curettement  of  the  pus  sinus.        (Radiograph  by  Lewis,  of  Chicago.) 


30.    Co  Observe  the  Tield  of  Operation  Before  and  After  flpicoectomy  (Root  Amputation). 

When  a  tooth  fails  to  respond  to  less  radical 
Tigs.  214  and  215.  treatment,  and  it  is  deemed  necessary  to  amputate  a 
portion  of  the  apex  of  the  root,  the  question  nat- 
urally arises,  how  much  of  the  root  shall  be  cut  off?  A  good  radiograph 
will  answer  this  question.  Fig.  214  shows  that  but  little  of  the  root 
heed  be  amputated.  Observe  that  a  great  amount  of  canal  filling  pene- 
trates the  apical  foramen.  Fig.  215  is  of  the  same  case  illustrated  in 
Fig.  214  immediately  after  the  operation. 

In  his  work  on  Materia  Mcdica  and  Therapcit- 
Tig.  216.  tics,  Dr.  Buckley  reports  an  interesting  case  of  apico- 

ectomy,  in  which  the  apex  was  amputated,  then  lost. 
A  radiograph  was  made.  (Fig.  216.)  Dr.  Buckley  says:  "This  radio- 
graph aided  materially,  as  it  verified  the  presence  of  the  root-end  and  its 
location." 


2     _ 


DENTAL  RADIOGRAPHY 


Radiographs  from  Dr.  Buckley's  Modern  Den- 
Tigs.  217  and  21$.       tal  Materia  Me  die  a,  Pharmacology  and  Therapeutics. 
They  are  exceptionally  good  pictures  taken  before 
and  after  amputation  of  the  apex. 

31.    to  Locate  foreign  Bodies,  Such  as  a  Broach  in  the  Pulp  Canal  or  tissue  at  the 
flpcx  of  a  tooth;  J\  Piece  of  Wooden  toothpick  in  the  Peridental  membrane,  etc. 

Case :    A  young  lady  about  twenty-five  years  of 

Tig.  219.  age.     Abscess  pointing  near  the  apex  of  an  upper 

central  incisor  carrying  a  post  porcelain  crown.     I 

suspected  that  the  canal  of  the  central  was  not  filled  properly,  and  made  a 


Fig.    219  Fig.  220  Fig.  221 

Fig.  21&.     Cement  and  gutta-percha — mostly  cement — in   an  abscess  cavity  at  the  apex  of  a  post- 
porcelain    crowned    central    incisor. 
Fig.  220.     Same  as  Fig.  219,  after  what   was  thought  to  be  all   of  the  cement   and  gutta-percha 
was   removed.      The   radiograph    shows   both   some   cement    (the   larger    shadow)    and   some   gutta- 
percha   (the   small    shadow)    still    remaining   in    the    abscess   cavity. 
Fig.   221.      The   same  as   Fig.    219,    showing   the   abscess   cavity    clear   of   all    foreign    bodies. 


radiograph  (Fig.  219)  to  learn  if  in  this  surmise  I  was  correct.  The 
radiograph  shows  the  canal  filled.  At  the  apex  of  the  root  can  be  seen  a 
large  abscess  cavity,  with  foreign  bodies  of  some  nature  in  it. 

An  incision  was  made  on  the  labial  aspect,  and 

fig.  220.  what  was  thought  to  be  afl  of  the  foreign  material, 

which  proved  to  be  cement  and  gutta-percha — mostly 

cement — was  removed  through  the  external  alveolar  plate.    A  radiograph 

'  Fig.  220 )  was  marie,  and  shows  some  cement  (the  larger  shadow)  and 

some  gutta-percha  (the  small  shadow;  still  in  the  abscess  cavity. 

These  bodies  were  removed  and  another  radio- 
fig.  221.  graph  (Fig.  221)  made  to  prove  that  no  foreign  irri- 
tating body  remained  in  the  abscess  cavity. 


THE  USES  OE  THE  RADIOGRAPH  IN  DENTISTRY     203 

The  pus  sinus  was  then  curetted,  washed,  cau- 
Tifl.  222.  terized,    injected    with   bismuth   paste,   and   another 

radiograph  (Fig.  222)  made.  All  of  this  work  was 
done  at  one  sitting,  and  consumed  about  two  hours'  time.  The  radiograph 
(Fig.  222)  shows  that  the  bismuth  paste  does  not  entirely  fill  the  abscess 
sinus.  It  has  been  my  experience  that  the  most  vigorous  and  earnest 
efforts  often  fail  to  "completely  fill"  an  abscess  cavity  with  bismuth  paste. 
The  manufacturers  of  the  paste  tell  us  that  "every  crevice"  must  be  filled 


Fig.  S22  Fig.  223 

Fig.    222.      Same   as   Fig.    219.      The   abscess   cavity    filled   with    bismuth   subnitrate    paste. 

Fig.    223.      Same    as    Fig.    219,    three    and    one-half    months    after    the    operation.      The    abscess 

cavity   is    entirely   filled    with   new   bone.      The   new   bone    is   as   yet    not   quite   as   dense   as    the 

surrounding    bone? 

or -the  paste  will  not  have  the  desired  curative  effect.  Every  crevice  that 
can  be  filled  should  be,  I  concede.  But  I  am  showing  you  a  case  now  in 
which  the  sinus  was  not  quite  filled,  and,  as  we  shall  see  presently,  the 
results  obtained  were  ideal.  Three  days  after  the  operation  another  in- 
jection of  bismuth  paste  was  made.  At  this  sitting  the  paste  was  not  in- 
jected under  as  much  force  as  the  previous  injection,  for  I  did  not  wish 
to  break  up  and  destroy  any  granulation  tissue  that  had  formed  along  the 
walls  of  the  sinus.  Another  injection  under  even  less  pressure  than  the 
second  was  made  at  the  end  of  four  days.  The  patient  returned  one  week 
after  the  third  injection  with  no  symptoms  of  her  former  trouble. 

Three  and  one-half  months  after  the  operation 

Tig.  223.  Fig.  223  was  made.    It  shows  a  most  remarkable  and 

gratifying  condition.     The  abscess  cavity  is  entirely 

filled  with  new  bone.    This  new  bone  is  as  yet  not  quite  as  dense  as  the 

Case:    Man  of  middle  age  had  suffered  obscure 

Tig.  224.  neuralgic  pams   for  about   a   month.      None  of   the 

teeth  on  the  affected  side  were  tender  to  percussion 


-'-'4 


DENTAL    RADIOGRAPHY 


or  pressure.  A  radiograph  (Fig.  224)  was  made  to  learn  whether  or  not 
the  canals  of  the  upper  second  molar  were  filled,  There  was  a  very  large 
amalgam  filling  in  this  tooth.  The  radiograph  does  not  show  the  roots  of 
the  molar  well,  hut  it  does  show  a  dark  shadow  between  the  second  and 
third  molars  just  above  the  cervical  margin  of  the  filling  in  the  distal  of 
the  second  molar.     On  Inquiry  it  was  learned  that  the  patient  was  in  the 


Fig.  221  Fig.  225 

Fig.    224.     The   arrow    points   into   a   piece    of   wooden    toothpick   between    the    second   and    third 

molars. 
Fig.   225.     The  upper  arrow  points  to  a  piece  of  broach   in  the  canal   of  the   upper   first  bicuspid. 
The  lower  arrow  points  to  a  piece  of  gutta-percha  passing  through  a  perforation  to  the  distal. 

habit  of  using  wooden  toothpicks.  Suspecting  the  shadow  to  be  a  piece 
oi  t'Xrthpick,  an  attempt  was  made  to  remove  it  with  explorers,  canal 
pluggers  and  silk  floss.  The  effort  met  with  failure,  but,  feeling  sure  that 
my  diagnosis  was  correct,  the  third  molar  was  extracted.  The  piece  of 
toothpick  adhered  to  the  extracted  tooth.  There  was  an  immediate  and 
complete  recovery  from  pain.* 

'Immediately  after  Fig.  224  appeared  in  the  May.  L912,  issue  of  Items  of  [n- 
terest,  Dr.  (  .  Edmund  Kells.  Jr.,  wrote  to  me  saying  there  must  be  some  mistake, 
that  wood  was  "absolutely  transparent"  to  the  X-rays,  and  that  according  to  the 
halftone,  Fig.  224,  the  piece  of  toothpick  casl  a  denser  shadow  than  the  amalgam 
filling  in  the  molar  tooth.  I  replied,  insisting  thai  wood  was  not  "absolutely  trans- 
parent" to  X-rays,  explaining  that  it  had  been  necessary  to  retouch  the  prim  to  make 
the  shadow  of  the  pick  show  at  all  in  the-  halftone,  and  enclosing  the  original  nega- 
1  the  case.  I  then  received  two  disassociated  molar  teeth  stuck  together,  side 
by  side,  with  pink  paraffin  and  wax.  and  a  piece  of  toothpick  in  the  wax.  parallel  to 
the  long  axis  ..f  the  teeth.  Also  a  radiographic  negative  of  the  teeth  and  a  letter 
from  l>r.  Kells,  saying  he  had  tried  to  make  a  radiograph  of  the  pick  and  had  failed. 
1  glanced  at  the  negative  and  could  sec  only  the  teeth  neither  the  wax  nor  the  piece 
of  pick  between  them,  I  made  a  radiograph  of  the  tesl  specimen  Dr.  Kells  had  senl 
me  and  succeeded  in  showing  both  the  wax  and  thai  part  of  the  ends  of  the  pieci  oi 
toothpick  which  extended  beyond  the  wax.  Thai  pari  of  the  pick  covered  with 
paraffin  and  wax  could  not  he  seen. 

I  was  talking  of  the  experimenl  and  showing  my  own  radiographs  to  a  dental 
studenl  The  student  asked  to  see  Dr.  Kells'  negative,  he  examined  it  and  said. 
"Why.  I  ran  see  the  same  thing  in  this  that  I  see  in  your  picture."  \nd  so  he 
could.  When  examined  close!}  Dr.  Kells'  negative  showed  the  ends  of  the  piece  of 
toothpick  extending  beyond  tin-  wax.  I  had  no)  examined  it  carefull)  enough  before 
— neither  had  Dr.  Kells. 

I  appreciate  tlie  interest  Dr.  Kells  takes  in  my  work,  and  I  thank  him  mosl 
earnestly  for  calling  mj  attention  to  what  seemed  to  be  a  mistake,  hut  having  radio- 
graphed a  piece  of  toothpick  experimentally,  I  shall  nol  retracl  anything  said  re- 
garding Fig.  224. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     205 

Case:    Young  woman,  had  been  in  the  hands  of 
Tig.  225.  an   incompetent   dentist,   who  had  treated  an  upper 

first  bicuspid  for  several  weeks,  and  had  finally  ad- 
vised its  extraction,  whereupon  the  patient  left  him,  presenting  to  me, 
and  asking  if  the  tooth  could  not  he  saved.  A  radiograph  (Fig.  225)  was 
made,  and  shows  a  piece  of  broach  in  the  canal  and  a  perforation  to  the 
distal  through  which  passes  a  gutta-percha  point.  About  the  end  of  the 
point  is  an  ahscess.     Owing  to  the  position  of  the  tube,  which  was  placed 


Fig.  226  Fig.  227 

Fig.    226.      Unremoved   mesial   root   of    a    lower    second   molar. 

Fig.    227.      The   radiograph    proves   the   absence   of   an    unremoved    root   of   the    lower    first   molar. 

too  high,  the  teeth  in  the  picture  are  too  short,  and  the  perforation,  which 
was  well  above  the  gum  line — too  far  to  be. detected — seems  to  be  just  at 
the  neck  of  the  tooth. 

I  agreed  with  the  "incompetent  dentist"  that  the  tooth  could  not  be 
saved.  The  condition  revealed  by  the  radiograph  could  not  have  been 
learned  by  any  other  means  save  extraction  and  dissection  of  the  tooth. 

32.    to  Determine  the  Presence  or  Absence  of  a  Bit  of  Root  Imbedded 
in  the  Gum  tissue. 

After  the  extraction  of  a  great  number  of  teeth,  or  after  having  been 
operated  upon  by  some  other  dentist,  a  patient  will  present  with  the  gum 
tissue  highly  inflamed  and.  pointing  to  the  inflamed  area,  say,  "Isn't  there 
a  piece  of  tooth  there  yet?"  Unless  the  X-rays  are  used  it  is  necessary 
to  anesthetize  the  parts  and  dissect  away  some  of  the  soft  tissues  to  de- 
termine whether  the  inflammation  may  be  due  to  an  unremoved  bit  of 
tooth  root,  an  unresorbed  spicula  of  process,  or  a  bit  of  process  fractured 
from  the  jaw.  This  requires  a  great  deal  of  time  and  work,  and  causes 
the  patient  unnecessary  pain.     The  radiograph  should  be  used. 

Case :    Much  swelling  of  the  face  on  the  affected 

Tig.  22b.  side.     The  patient  was  unable  to  open  the  mouth  to 

any  extent  without  considerable  pain.     Two  weeks 


_'l  II I 


DENTAL   RADIOGRAPHY 


Fig.    228.      This    radiograph    is    of    a    dry    subject.      Pictures    of    dry    bones    show    clearly    because 

tbere    are    no    soft    tissues    to    penetrate.      The    third    molar    is    badly    impacted    in    the    ramus. 

(Radiograph    by    Oyer,    of    Philadelphia.) 


previously  the  lower  second  molar  on  the  affected  side  had  been  extract- 
ed i  ?)  by  a  quack  dentist.  The  question  naturally  arose,  "Has  all  of  the 
second  molar  been  removed?"  A  radiograph  (Fig.  226)  was  made,  and 
-hows  that  the  mesial  root  still  remains.  It  was  taken  out,  and  the  case 
recovered  promptly.  The  advantages  derived  from  using  the  radiograph 
in  thi>  case  were  as  follows:  It  saved  the  patient  the  pain  of  opening  the 
mouth  for  a  prolonged  instrumental  and  ocular  examination;  and  also 
the  pain  caused  by  lancing,  dissecting,  and  probing  incident  to  such  an 
examination.  It  saved  both  the  patient  and  the  operator  time.  It  showed 
clearly  and  exactly  how  much  of  the  tooth  was  left,  and  illustrated  its 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY    207 

exact  location.     It  made  the  extraction  of  the  piece  of  root  decidedly 
easier  for  both  patient  and  operator. 

Fig.  22~  is  of  a  case  similar  In  that  shown  in 
Tigs.  227  and  22$.  Fig.  226.  In  this  case,  however,  the  second  molar 
had  been  extracted  a  year  previously,  and  the  radio- 
graph shows  no  unremoved  bit  of  tooth  root.  The  radiograph  fails  to 
disclose  a  cause  for  the  clinical  signs.  But  let  me  impress  you  with  this 
fact :  it  does  show  that  an  unremoved  bit  of  tooth  root  is  not  the  cause, 
and  so  aids  us  very  greatly  in  a  diagnosis  by  elimination.    The  patient  did 


Fig.   229.     A  piece  of  tooth   root  and  an   impacted   cuspid   in*  an  otherwise   edentulous   upper   jaw. 
(Radiograph    by    Lewis,    of    Chicago.) 


not  return  after  his  first  visit,  so  the  case  was  never  diagnosed.  There 
may  have  been  a  third  molar  impacted  in  the  ramus.  (See  Fig.  228.) 
No  one  can  deny  the  possibility.  We  took  only  the  first  step  toward  diag- 
nosis— we  eliminated  a  possible  cause. 

Though  I  have  been  unable  to  obtain  a  definite 
Tig.  229.  history  of  this  case,  it  is,  in  all  probability,  about  as 

follows :  After  the  extraction  of  the  upper  teeth  the 
patient  returned  with  a  localized  inflammation  of  the  gum  tissue  in  the 
cuspid  region.  A  radiograph  was  made  to  learn  if  this  inflammation  was 
caused  by  an  unresorbed  bit  of  process  or  a  piece  of  tooth  root.  The 
picture  shows  not  only  a  piece  of  tooth  root,  but  also  an  impacted  cuspid 
tooth.  It  is  not  unlikely  that  this  patient  suffered  from  obscure  neuralgic 
pains,  headache,  or  other  nerve  affections. 

Notice  the  bit  of  root  imbedded  in  the  process. 

My  chief  reason  for  exhibiting  this  picture  is  because 
it    shows    so   clearly    the   gum    tissue   overlying   the   process. 


Tig.  230. 


_  8  DENTAL    RADIOGRAPHY 

A  piece  of  root,  one  end  of  which  rests  on  the 

fig.  231.  edge  of  an  ill-titling  shell  crown,  the  other  against 

the  cuspid  tooth.     The  inflammation  caused  by  this 

root  extends  up  to  the  apex  and  to  the  mesial  of  the  cuspid.     In  such  a 

position  the  root  could  never  have  dropped  down  to  where  it  could  be 

seen  in  the  month. 


Fig.  230  Fig.  231 

Fig.   2:w.     The  arrow   points   to  a  bit  of  tooth   root.      Notice   how   clearly   the   gum   tissue   shows 

in    this    radiograph.       (Radiograph    by    Ream,    of    Chicago.) 

Fig.    231.      A   bit   of  tooth   root,   one   end   resting  on  the   edge   of   an    ill-fitting   shell    crown,    the 

other  against  the  cuspid.     The  abscess  caused  by  this  piece  of  root  extends  to  the  apex  and  to 

the  mesial  of  the  cuspid.      (Radiograph  by   Blum,   of  New  York  City.) 

33.    Co  Diagnose  fracture  of  a  Root. 

Within  the  same  week  two  cases  in  which  the 
Tigs.  232  and  233.  upper  anterior  teeth  had  sustained  a  severe  blow  pre- 
sented at  the  college  clinic  for  treatment.  In  one  case 
a  lateral  incisor  (Fig.  232),  and  in  the  other  case  both  centrals  (Fig.  233) 
\\ei\-  very  loose.  Radiograph  Fig.  232  shows  the  root  of  the  lateral 
fractured.  Extraction  is  indicated.  Radiograph  Fig.  2^^  shows  that 
the  roots  of  the  centrals  are  not  fractured.  Extraction  is  contraindicated. 
1  As  can  be  seen  in  the  radiograph,  both  central  crowns  are  broken  off,  and 
one  lateral  is  knocked  out  completely.)  It  will  be  appreciated  that  the 
radiographic  findings  in  these  cases  governed  completely  our  course  of 
treatment.  I  would  suggest  it  as  a  most  rational  expedient  that  radio- 
graphs be  taken  in  all  cases  of  traumatism,  before  treatment  is  begun. 

Case:    Young  lady  fell  on  dance  hall  floor  strik- 

?i(j.  234.  ing  the  upper  centrals  and  loosening  them.   Her  den- 

tisl  treated  both  teeth,  removing  inflamed  pulps.  One 

tooth  progressed  promptly  to  recovery,  but  the  other  remained  loose  and 

Vfter  several  week-  of  treatment  the  patient  presented  to  Dr.  F.  B. 

Moorehead,  of  Chicago,  who  had  a  radiograph  made  before  commencing 

treatment.     The  radiograph  shows  the  root   of  the  loose  tooth    fractured 


THE  USES  OE  THE  RADIOC K.  U'/I  IN  DENTISTRY     209 

near  the  apex.  Dr.  Moorehead  removed  the  apex  of  the  root  through  the 
external  alveolar  plate,  smoothed  the  end  of  the  broken  root,  and  the  case 
recovered  promptly.  It  is  almost  superfluous  to  do  so,  yet  I  want  to  call 
your  attention  to  the  fact  that  this  case,  like  very  many  others  I  have  re- 
ported, could  not  have  been  diagnosed  and  treated  properly  without  using 
the  radiograph. 


Fig.  233 


Fig.  234 


Fig.    232.      Fractured    upper    lateral    incisor.      Because    of    the    location    of    the    break    extraction 

is    indicated. 

Fig.   233.      It   was   thought  that   the   roots   of  the   centrals  were   fractured.      The   radiograph   shows 

they   are    not.  • 

Fig.    234.      Left   central   fractured   near   the   apex.      The   case   had   been   treated   for   alveolar   ab- 
scess   without    success    for    several    weeks.       The    removal    of    the    piece    of    fractured    root-end 
through    the    external    alveolar    plate    effected    a    cuic.       (Radiograph    by    Lewis,    of    Chicago.) 


34.    Co  Observe  the  Size  and  Shape  of  Roots  of  teeth  to  be  Used  in  Grown 

and  Bridgework. 

Malformed     upper     laterals — "peg     laterals" — 
Tig.  235.  occur   quite    frequently.      Their   appearance    is   bad, 

and,  for  esthetic  reasons,  we  often  crown  them.  The 
porcelain  jacket  crown  is  difficult  to  construct  and,  at  best,  fragile.  If 
the  root  of  the  peg  lateral  is  long  enough  a  post  porcelain  crown  of  some 
kind  is  indicated  in  preference  to  the  porcelain  jacket.  Fig.  235  shows 
a  peg-shaped  lateral.  In  this  case  the  root  is  long  enough  to  permit  of 
the  introduction  of  a  post  into  the  canal  a  sufficient  distance  to  insure 
stability  of  a  post  crown.  The  root  is  somewhat  tortuous,  but,  with  the 
radiograph  to  guide,  the  operator  should  be  able  to  enlarge  the  canal  suffi- 
ciently, without  clanger  of  making  a  perforation  into  the  pericemental 
membrane. 


210 


DEXTAL   RADIOGRAPHY 


Before    using    teeth    as    abutments    for    large 
Tig.  23fr.  bridges,  it  would  not  be  unwise  to  make  radiographs 

to  note  the  size  of  the  roots.  It  would  be  a  mistake, 
I  believe,  to  use  such  a  tooth  as  the  malformed  one  shown  in  Fig.  236  as 
an  abutment  for  a  bridge  of  any  extent.  It  should  be  borne  in  mind  that 
unless  the  pose  is  exactly  right — and  we  seldom  have  it  so — the  teeth,  as 
they  appear  on  the  radiograph,  do  not  represent  definitely  the  exact  length 
of  the  teeth  themselves.  Nevertheless,  the  radiograph  does  give  us  a 
fairly  definite  idea  of  the  relative  length  of  the  teeth. 


Fig.  235  Fig.  230 

Fig.   235.     A  peg  lateral,   the  root  of   which   is  somewhat   tortuous.      (Radiograph   by   Blum, 

of    New    York    City.) 

Fig.   23G.     A  malformed   cuspid   tooth.      It   would   be   a   mistake   to   use   such    a    tooth   as  an 

abutment    for    a    large   bridge. 


35.    fls  an  Aid  and  Safeguard  Ulbcn  enlarging  Canals  for  Posts. 

There  are  times  while  enlarging  canals  for  posts  when  we  lose  the 
course  of  the  canal  and  are  much  disturbed  to  know  if  we  are  making  our 
enlargement  in  the  proper  direction.  Place  a  wire  in  the  canal  and  make 
a  radiograph.  If  the  enlargement  is  being  made  to  the  mesial  or  distal, 
with  danger  of  a  perforation,  this  can  be  seen  in  the  picture.  One  might 
completely  penetrate  the  side  of  the  root  towards  the  labial,  or  buccal,  or 
lingual,  without  being  warned  of  the  danger  by  a  radiograph,  but,  bear  in 
mind,  perforations  made  through  the  side  of  a  root  are,  with  rare  excep- 
tions, either  to  the  mesial  or  distal. 

In    Fig.    237,    observe    the    central    carrying    a 

fig.  237.  Post  porcelain  crown.    The  post  does  not  follow  the 

canal.     Had  the  enlargement  for  it  continued  in  the 

same  direction  as  was  started,  the  dentist  would  have  penetrated  the  side 

of  the  root.    A  radiograph  of  this  case  would  have  enabled  the  operator 

to  see  his  mistake  and  correct  it. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     211 

This  radiograph  shows  a  perforation  through  the 
Tifl.  23$.  side  of  the  root,  to  the  distal,  in  an  upper  second  bi- 

cuspid. The  perforation  was  made  when  enlarging 
the  canal  for  a  post.  A  probe  passes  through  the  side  of  the  root,  up  into 
an  abscess  cavity  at  the  apex  of  the  tooth. 

The  radiograph  is  an  aid  not  only  when  we  are  enlarging  canals  for 
posts,  but  also  when  we  are  removing  posts  from  canals.  It  shows  us 
how  long  the  post  is,  and  how  much  tissue  we  can  cut  away  from  the  sides 
of  it  in  safetv. 


Fig.  237  Fig.  238 

Fig.  237.     The  post  in  the  post-porcelain  crowned  central  does  not   follow  the   canal.      It   almost 

penetrates   the    side   of   the    root.      (Radiograph    by    Graham,    of    Detroit.) 

Fig.    238.      Perforation    through    the    side    of   the   root    of   a»  upper    second    bicuspid.      A    probe 

passes  through   the   perforation.      (Radiograph   by  Graham,    of   Detroit.) 

36.    to  Examine  Bridges  About  Which  there  Ts  Jin  Inflammation. 

At  best  fixed  bridges  are  not  sanitary.  For  this 
Tigs.  239  and  240.  reason  we  often  find  an  intense  inflammation  about 
them.  Thorough  depletion  by  scarifying  and  the  use 
of  an  astringent,  antiseptic  mouthwash  will  usually  give  prompt  relief. 
There  may  be  causes  for  the  inflammation  other  than  the  simple  fact  that 
the  bridge  is  a  foreign  body  in  the  mouth,  making  thorough  cleanliness 
impossible.  Observe  Figs.  129,  239  and  240  as  examples.  It  would  be 
extremely  difficult  to  remove  the  bit  of  root  shown  beneath  the  bridge  in 
Fig.  239  without  removing  the  bridge.  The  piece  of  root  shown  in  Fig. 
240  can  easily  be  removed  through  the  external  alveolar  plate  without 
removing  the  bridge. 

I  have  recently  heard  of  a  case  in  which  a  very  severe  inflammation 
existed  about  a  bridge  which  had  only  been  set  for  about  a  week.  The 
case  was  treated  for  several  days,  and  finally  the  bridge  removed  when  it 
was  seen  that,  at  the  time  the  bridge  was  set,  a  considerable  quantity  of 


212 


DENTAL   RADIOGRAPHY 


cement  had  been  forced  into  the  tissues  near  a  shell  crown  abutment.  Re- 
moval of  this  cement  effected  a  prompt  cure.  Had  a  radiograph  been 
made,  the  cause  of  the  trouble  would  have  been  seen  immediately,  and, 
depending  on  the  exact  location  of  the  cement,  removal  of  the  bridge  may 
have  been  avoided. 


Fig.  239 


Fig.  240 


Fig.   239.     A   piece  of  tooth   root   in   the  tissues  beneath    a   bridge.      (Radiograph   by   Lewis, 

of    Chicago.) 
Fig.   240.      A  piece  of  tooth  root  in   the  tissues  above  a  very  large  bridge.      It   would   be   easily 
possible  to   remove  it  through  the  external  alveolar  plate   without  removing  the   bridge.      (Radio- 
graph  by   Lewis,    of   Chicago.) 


37.    Co  Observe  the  field  Before  Constructing  a  Bridge. 

Tin's  use  of  the  radiograph  has  already  been  illustrated — Figs.  129, 
239,  and  240.  The  radiograph  will  not  only  disclose  the  presence  of  un- 
erupted  teeth,  and  unremoved  pieces  of  tooth  roots,  but,  as  has  been  sug- 
gested under  another  heading,  it  will  also  show  the  operator  the  size,  shape 
and  health  of  the  roots  of  the  teeth  he  is  using  for  abutments. 


38.    Co  Observe  Planted  Ceetb. 
Case:    One  in   the  practice  of  Dr.  C.  Edmund 
Tigs.  241  and  242.       Kells,  Jr..  Fig.  241,  shows  a  fracture  of  the  root  of 
a  lateral,  the  result  of  a  fall.     After  the  two  pieces 
of  the  lateral  were  extracted  they  were  united  and  held  together  with  an 
iridio-platinum  -crew  set  in  cement,  and  the  repaired  rout  then  replanted. 
The  radiograph  |  li.L,r.  242)  was  made  immediately  after  the  operation.    A 
gold  splint  i->  seen  covering  the  crown  of  the  cuspid,  lateral  and  both  cen- 
trals. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY    213 

A  case  of  replantation  of  a  lower  second  bicus- 
Tig.  243.  pi«l  two  years  and  four  months  after  the  operation. 

The  root  is  almost  entirely  absorbed.  Notice  how 
plainly  the  pericemental  membrane  can  be  seen  about  the  roots  of  the  first 
bicuspid  and  first  molar,  appearing  as  a  light  line.  Notice  also  the  ab- 
sence of  this  line  about  the  remaining  portion  of  the  root  of  the  replanted 
tooth. 

The  theory  of  the  attachment  of  planted  teeth  is  as  follows :     The 
roots   of   the   planted   teeth   are   absorbed   at   different   points,   and   bone 


Fig.   241.  Fig.   242. 

Fig.    241.      Fracture    of   upper    lateral    incisor.      ( Radiograph    by    Kells,    of    New    Orleans.) 

Fig.    242.      Same  as   Fig.    241    after   the   removal   of   the   lateral   and    its   replantation.      Radiograph 

by  Kells,  of  New  Orleans.) 

immediately  fills  into  these  places,  so  holding  the  tooth.     Hence,  planted 
teeth  do  not  have  a  pericemental  membrane.     Radiographic  findings  bear 

out  this  theory.  ,-,.  ,  .      ,    ,  .   .  .-, 

rig.  244  shows  an  implanted  porcelain  root.    Ob- 
fig.  244.  serve  that  the  root  has  practically  no  bony  attachment 
at  all,  and  would  drop  out  save  for  the  manner  in 
which  it  is  splinted  to  the  other  central. 

Dr.  E.  G.  Greenfield.  Wichita,  Kas..  has  designed 
Tig.  245.  and  manufactured  a  sort  of  cage-like  root  of  iridio- 

platinum  wire  to  be  used  for  implantation.  So  far 
all  forms  of  artificial  roots  for  teeth  have  proven  failures,  but  this  one 
bids  fair  to  be  a  success.  Whether  it  will  be  a  success  or  not  depends  on 
whether  or  not  bony  tissue  will  build  in  and  about  the  wires.  The  radio- 
graph (Fig.  245)  is  introduced  more  for  the  purpose  of  showing  the  arti- 
ficial roots  than  for  any  other  reason.  The  radiograph  has  not  been  made 
in  such  a  way  as  to  enable  us  to  see  whether  there  is  an  osseous  deposit 
within  the  wires  or  not. 


214 


DEXTAL  RADIOGRAPHY 


39.    Tn  eases  of  Cementoma. 
Cementomata  (or  cases  of  hypercementosis,  as  they  are  often  called) 
are  sometimes  the  cause  of  neuralgia.    There  are  no  means  at  our  disposal 
whereby  they  (cementomata)   can  be  diagnosed  save  by  the  use  of  the 
radiograph. 


***rr. 


V 


Fig. 


Fig.   244. 


Fig.  243.     A  case  of  replantation  of  the  lower  second  bicuspid  two  years  and  four  months  after 

the  operation.     The  root  is  almost  entirely  absorbed.      (Radiograph  by   Kells,   of   New   Orleans.) 

Fig.    244.      Artificial   porcelain   root  with   no   bony   attachment   at  all    save   just   at   the   apex. 

(Radiograph  by  Ream,  of  Chicago.) 


These  radiographs  illustrate  cementomata,  which 
Tigs.  246  and  247.       were  responsible  for  persistent  neuralgias.     Extrac- 
tion was  necessary  in  both  cases. 

40.    Tn  Gases  of  Bone  "Ulborls." 

The  term  bone  whorl  is  used  to  designate  particularly  dense  areas  of 
bone  occurring  in  bone.  Bone  whorls  may  be  caused  by  a  prolonged,  mild 
irritation,  like  that  produced  by  an  impacted  tooth,  for  example.  They 
are  sometimes  responsible  for  facial  neuralgia.  In  answer  to  a  letter  ask- 
ing him  if  be  ever  found  it  necessary,  or  ever  expected  to  find  it  necessary, 
to  open  into  the  bone  and  surgically  break  up  whorls  to  relieve  neuralgia, 
1  )r.  Cryer  replies,  "I  have  found  it  necessary  in  several  cases  to  open  into 
the  bone  and  remove  the  whorls,  or  bard  bone,  and   I    fully  expect  to  do 

rain."  From  the  nature  and  location  of  whorls,  it  is  obvious  that  they 
can  be  found  only  by  the  use  of  the  radiograph. 


THE  USES  OE  THE  RADIOGRAPH  IN  DENTISTRY     215 

A  case  in  the  practice  of  Dr.  Oyer.    The  patient 
Tigs.  248  and  249.       was  suffering  from  pain  on  one  side  of  the  face.    A 
radiograph   of   the   case    (Fig.   248)    shows   an   im- 
pacted lower  third  molar.    It  was  thought  hest  to  remove  the  second  molar 


Fig.    245.      Two   artificial   roots   implanted   in    the   «ppe\  jaw.      (Radiographer   not    known.) 


Fig-   -M...  Fig.   247. 

Fig.  246.      Cementoma  on  lower,  second,  shell-crowned  molar.    (Radiograph  by  Ream,   of   Chicago.) 
Fig.    247.      Cementoma.      (Radiograph    by    Ream,    of    Chicago.) 

first,  then  the  third  molar.  This  was  done,  and  the  neuralgia  disappeared 
for  about  ten  days,  then  pain  returned.  Another  radiograph  (Fig.  249) 
was  made  which  shows  a  bone  whorl  in  the  region  from  which  the  second 
molar  had  been  removed.  Another  operation  was  done  removing  the 
whorl,  after  which  the  neuralgia  disappeared  altogether. 


2l6 


DENTAL   RADIOGRAPHY 


Fig.  248.     An  unerupted  lower  third  molar.     The  arrow  points  to  a   bone  "whorl."      (Radiograph 

by  Pancoast,   of   Philadelphia.) 


Case  in  the  practice  of  Dr.  Robert  H.  Ivy,  of 
fjg.  250.  Philadelphia.     "The  patient  had  suffered  from  neu- 

ralgia of  the  mandibular  division  of  the  fifth  nerve 
on  the  right  side,  for  two  years.  In  February,  191 1,  she  was  treated  by 
an  alcohol  injection  of  thi>  division,  which  gave  relief  from  pain  for  six 
months,  after  which  the  trouble  returned,  but  not  so  severely  as  before. 
In  January,  1912,  a  skiagram  was  made,  showing  a  dense  spot  in  the 
n  of  the  first  molar  tooth,  and  in  close  relation  to  the  inferior  dental 
nerve.  This  is  so  dense  as  to  appear  like  a  piece  of  tooth  root,  but  when 
cut  down  upon  with  the  surgical  engine,  nothing  but  dense  bone  was 
found.  The  patient  has  been  without  neuralgia  since  the  operation,  though 
it  is  too  soon  yel  to  say  whether  the  relief  will  be  permanent." 


THE  USES  OF   THE  RADIOGRAPH  IX  DENTISTRY     217 


Fig.    249.      The   same   as    Fig.    248    after    the    extraction    of    the    lower    second    and    third    molars. 

The   arrow    points    to    a    dark,   three-sided    shadow — a    bone    "whorl."      The    X    on    the    shadow    is 

caused   by   a    scratch    en   the   negative.      (Radiograph   by    Pancoast,    of    Philadelphia.) 


41.    to  Locate  Stones  (Calculi)  in  the  Salivary  Ducts  or  Glands. 

The  history  of  this  case  given  me  by  Dr.  Sidney 
Tifl.  251.  Lange,  of  Cincinnati,  Ohio,  is  as  follows:     Patient, 

female,  age  about  forty,  suffered  recurrent  attacks  of 
swelling  and  pain  in  the  region  of  the  submaxillary  gland  on  one  side. 
The  attacks  seemed  to  follow  the  taking  of  sour  foods.  A  radiograph 
(Fig.  251)  was  made.  The  arrow  points  to  a  stone  in  the  submaxillary 
duct.  Because  the  patient  had  had  a  stone  removed  from  the  same  duct 
several  years  previously,  and  because  the  gland  was  considerably  thick- 
ened, simple  removal  of  the  stone  was  thought  to  be  contraindicated,  and 
a  more  radical  operation  involving  the  removal  of  the  entire  gland  was 
performed. 


218 


DEXTAL   RADIOGRAPHY 


42.    Tn  Cases  of  Bone  Cysts. 

"A  cyst  is  an  organized  structure  consisting  of  a  sac-like  wall  to- 
gether with  its  contents,  especially  one  of  pathological  formation  or 
abnormal  development." — Appleton's  Medical  Dictionary. 


The    dark    shadow    to    which    the    arrow    points    is    a    bone    "whorl.' 
Pancoast,   of    Philadelphia.) 


(Radiograph    by 


According  to  this  definition  all  chronic  alveolar  abscesses  are  cysts — 
hone  cysts,  because  they  occur  in  bone.  But  the  name  cyst  is  usually  not 
applied  until  the  abscess  sac  assumes  a  great  size.  The  abscess  in  Fig. 
[93  i-  large  enough  to  he  called  a  cyst,  in  the  generally  used  sense  of  the 
term. 

This  radiograph  shows  a  large  cyst  in  the  lower 
j\%.  252.  jaw.     Tlie  two  roots  of  the  lower  first  molar  are 

doubtless  responsible  for  tin-  cyst  formation. 
In  cyst  case-  there  i-  often  considerable  and  disfiguring  enlargement 
of  the  bone,  and  such  cases  are  spoken  of  as  cystic  tumors,  a  tumor,  of 
course,  being  simply  an  abnormal  enlargement  or  growth. 


THE  USES  OF  THE  RADIOGKAI'II  IN  DENTISTRY    219 

A  man,  age  about  thirty-seven,  was  referred  to 

Tigs.  253  and  254.       the  college  clinic  "to  have  a  growth  on  the  lower  jaw 

cut  off."    There  was  no  "growth"  to  "cut  off."  There 

was  a  definite  enlargement  of  the  bone  in  the  lower  first  molar  region. 


Fig.    251.     The    arrow    points    to    a    stone    in    the    submaxillary    duct.       (Radiograph    by    Lange,    of 

Cincinnati.) 


giving  the  man  the  appearance  of  carrying  a  large  lump  of  tobacco 
in  the  vestibule  of  the  mouth.  The  patient  suffered  local  pain,  and  the 
involved  area  was  tender  to  palpation.  The  first  molar  tooth  was  missing 
from  the  jaw.  A  radiograph  was  made  and  showed  a  cyst  involving  the 
second  bicuspid  and  second  molar.  (I  regret  that  the  radiograph  has  been 
lost.)  Neither  the  second  bicuspid  nor  the  second  molar  had  cavities  nor 
fillings  in  them.  Considering  the  evidence  of  neglect  of  the  mouth  and 
teeth,  it  was  not  deemed  worth  while  to  try  to  conserve  the  teeth.  Ac- 
cordingly the  second  bicuspid  was  extracted,  which  permitted  the  escape 
of  considerable  watery,  brown  pus.  A  doubt  then  arose  as  to  whether 
the  radiograph  showed  an  involvement  of  the  molar  or  not.  Another 
radiograph  (Fig.  253)  was  made.  It  shows  that  the  molar  is  involved. 
It  was  extracted  and  more  serous  pus  evacuated.     Antiseptic  solutions 


220 


m:\r.iL  kj  d  i  o  g  R;  why 


could  now  be  washed  from  one  tooth  socket,  through  the  cyst,  and  out  at 
the  other  tooth  socket.  The  cyst  was  curetted,  cauterized  and  packed  with 
sterile  gauze.  Healing  except  from  within  outward  was  prevented  by  the 
use  of  gauze,  and  the  case  recovered.    Relief  from  pain  and  soreness  was 


Fig.    252.      Large   cyst   in   the   lower   jaw.      The    more    or    less   oval-shaped    light    area    represents 
the  cyst.      (Radiograph   by    Lewis,   of  Chicago.) 


Fig.   253.  Fig.   254. 

Fig.   253.     A  bone  cyst   in   the   lower  jaw. 
Fig,   254.     Same  as   Fig.  ■.'•">:;.  with  the  cyst  outlined  to  enable  the  reader  to  observe  Fig.  258  to 
advantage.     The  circle   A   is  the  alveolus   from  which  the  second   bicuspid  was  extracted. 


immediate.     It  required  two  or  three  months  for  all  of  the  enlargement 
of  the  jaw  to  disappear. 

hi  my  experience  a^  a  radiographer  I  have  observed  that  the  general 

practitioner   of    dentistr)    shows   great    reluctance   to   extract    a   tooth,   no 
matter  what  the  condition  he  is  treating  may  he.     On  the  other  hand,  the 


77//:'  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     221 

specialist  in  oral  surgery  extracts  teeth  sometimes  without  making  the 
slightest  effort  to  conserve  them.  I  believe,  however,  that  the  oral  surgeon 
is  less  often  mistaken.  A  man  may  make  a  greater  mistake  than  the  ex- 
traction of  a  tooth.  For  example :  failure  to  extract  a  tooth  which  is 
causing  otherwise  incurable  suppuration,  general  sepsis,  nervous  dis- 
orders, necrosis  or  distracting  pain. 


Fig.   Cio.      A  very  large   cyst  of  the  lower  jaw.      The   light  area   represents  the   cyst.      This   radio- 
graph   shows    the    hyoid    bone.    (Radiograph    by    Lange,    of    Cincinnati.) 


Dr.  Sidney  Lange.  of  Cincinnati,  made  the  radio- 
Tig.  255.  graph  shown  in  Fig.  255,  but  did  not  treat  the  case. 
Dr.  Lange  was,  however,  able  to  furnish  the  follow- 
ing history :  Patient,  boy.  about  eighteen.  Very  large  swelling  in  the 
lower  jaw.  Xo  pain  or  tenderness  in  the  region  of  enlargement.  A  radio- 
graph (  Fig.  255)  was  made,  and  the  case  diagnosed  as  a  "benign  bone 
cyst."     The  boy  was  taken  to  a  hospital  and  the  cyst  drained  of  a  straw- 


222 


DENTAL   RADIOGRAPHY 


colored  fluid,  curetted  and  packed  with  gauze,  through  an  opening  made 
inside  of  the  mouth  to  the  buccal.  The  patient  left  the  hospital  in  a  week 
or  two  after  the  operation. 

Case:     Male,  age  about  twenty-five.     Enlarge- 

J\Q.  2$b.  ment  of  the  mandible  at  the  symphysis.     Tenderness, 

intermittent  local  pains.     The  radiograph  shows  a 

large  cyst.     Failing  to  keep  an  appointment,   the  patient   has  not  been 

heard  of  since  the  radiograph  was  made. 


Fig.    256.     Bone   cyst   of   the    lower    jaw. 


43.    In  Cases  of  Dentigerous  Gyst. 

Any  cyst  containing  a  tooth  body,  or  tooth  bodies,  is  said  to  be  a 
dentigerous  cyst.  Dentigerous  cyst  of  the  jaws  are  not  uncommon.  Their 
definite  diagnosis  is  possible  only  when  the  radiograph  is  used. 

Because  the  apex  of  the  tooth  extends  into  the  pus  sac  a  chronic 
dento-alveolar  abscess  is  sometimes  called  a  dentigerous  cyst.  But  this 
use  of  the  term  is  considered  improper. 

Case  in  the  practice  of  Dr.  M.  II.  Oyer.    I  quote 

fig.  257.  Dr.   Cryer:     "The  patient,  a  child  of  nine,  had  a 

swelling  of  the  left  side  of  jaw  for  about  two  years. 

This  gradually  increased  to  the  sizr  of  a  hen's  egg,  causing  considerable 

deformity.     A  radiograph  of  the  case  (Fig.  2^j  |  shows  a  retained  de- 


THE  USES  OF  THE  RADIOGRAPH  IX  DENTISTRY     223 


Fig.   257.      Dentigerous  cyst  of  the   lower  jaw  in  child   nine   years   old.      The   arrow   points   to   the 
tooth  in  the  cyst.  The  light  area  represents  the  cyst.    (Radiograph  by  Pancoast,  of  Philadelphia.) 


ciduous  second  molar  tooth  at  the  lower  border  of  the  jaw  and  surrounded 
by  an  ovoid  clear  area.    A  diagnosis  of  dentigerous  cyst  was  made. 

"At  operation  through  the  mouth  the  shell  of  bone  was  found  to  con- 
tain, not  the  usual  fluid,  but  a  resilient  mass  of  pinkish-white  tissue  sur- 
rounded by  a  sac  of  darker  color.  The  contents,  including  the  soft  tissues, 
the  tooth  shown  in  the  picture  and  the  sac,  were  removed  and  the  cavity 
lightly  packed  with  gauze.  The  patient  is  making  an  uneventful  recovery. 
The  further  diagnosis  of  the  case  will  depend  on  microscopic  examination 
of  the  tissue." 

Fig.  258  was  made   for  a  patient  of  Dr.  J.  G. 
Tigs.  258  and  259.       Lane,  of  Philadelphia.     Age  of  patient,  eight.     The 
radiograph  shows  an  unerupted  second  bicuspid  sur- 
rounded by  a  light  area  representing  a  dentigerous  cyst.     The  upper  wall 


224 


DENT.  II.    RADIOGRAPHY 


- 


A   dentigerous   cyst   containing   a   lower   second   bicuspid. 
of    Philadelphia.) 


(Radiograph   by    Pancoast, 


of  the  cyst  and  its  fluid  contents  were  removed,  leaving  the  tooth  in  place. 
A  later  radiograph  I  Fig.  259)  shows  that  the  tooth  is  gradually  erupting 
into  position.     (This  history  is  quoted  from  a  paper  by  Dr.  Cryer.) 

44.    In  eases  of  tumor,  Benign  or  malignant. 

1  have  already  reported  a  case  of  cystic  tumor,  which  was  referred 
to  the  college  clinic  to  have  the  tumor  "cut  off."  There  was  nothing  to 
"cut  off,"  and  a  radiograph  showed  a  cavity  in  the  hone,  aspiration  of 
which  accomplished  a  cure. 

The  following  cases  occurred  in  the  practice  of 
fig.  260.  Dr.  Cryer:    "The  two  patients  were  sent  by  different 

practitioner-  from  different  portions  of  the  State  of 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     22s 


Fig.    259.      Same    as    Fig.    25S    after    removal    of    the    fluid    contents   and    upper    wall    of   the    cyst, 
showing  the   second   bicuspid    erupting   into  place.      (Radiograph   by   Pancoast,   of   Philadelphia.) 


Pennsylvania,  but  came  for  examination  on  the  same  day.  They  were 
two  women  patients  of  about  the  same  age,  both  wearing  full  upper  arti- 
ficial dentures  and  partial  lower  ones,  and  both  suffering  from  a  similar 
character  of  pain,  the  only  difference  being  that  in  one  patient  the  pain 
was  located  on  the  left  side  of  the  lower  jaw,  while  the  other  was  on  the 
right  side  of  the  lower  jaw.  Physical  examination  revealed  the  fact  that 
the  right  cervical  lymphatic  glands  in  one  of  the  patients  were  slightly 
enlarged.  The  history  obtained  of  the  cases  did  not  aid  in  diagnosis. 
Both  patients  claimed  that  the  molar  teeth  on  each  side  had  been  ex- 
tracted years  ago.  X-rays  were  made  of  the  jaws  with  the  following 
results : 

"Fig.  260  was  made  from  the  patient  whose  cervical  glands  were 


226 


DEXT.1L    RADIOGRAPHY 


Fig.   200.     Myelosarcoma   of  the   lower   jaw.      In   appearance   it   resembles  a   bone  cyst   somewhat. 
(Radiograph   by    I'ancoast,    of    Philadelphia.) 


enlarged.  The  picture  shows  a  breaking  down  of  the  bone,  with  the  two 
dark  shadows  indicating  abnormal  density  of  the  bone  in  some  portions. 
From  tin-  appearance,  together  with  the  slight  enlargement  of  the  glands, 
the  case  was  diagnosed  as  myelosarcoma.  A  microscopic  examination  of 
the  tissue  removed,  confirmed  the  diagnosis." 

I  do  not  reproduce  the  radiograph  of  the  other  case  because  the  print 
I  have  i-  not  dear  enough  to  permit  of  a  good  halftone  reproduction.  The 
print  before  me  shows  fairly  well  three  impacted  lower  teeth,  one  a  rudi- 
mentary bicuspid,  the  others  a  second  and  third  molar. 


THE  USES  OF  THE  RADIOGRAPH  IX  DENTISTRY     227 

Dr.  Cryer  says:  "There  seemed  to  be  very  little  difference  in  these 
two  cases  from  the  history  and  physical  examination,  but  the  wonderful 
work  of  the  X-rays  revealed  a  very  great  dissimilarity.  On  the  one  hand 
the  skiagraph  indicated  the  sad  necessity  of  removing  the  entire  right  side 
of  the  jaw  and  submaxillary  lymphatic  glands,  with  the  possibility  of  the 
disease  returning,  while  in  the  other  case  the  extraction  of  the  three  im- 
pacted teeth  was  the  only  thing  required." 


Fig.  261.  Fig.  862. 

Fig.   261.      Osteoma    (?)    of   the  lower  jaw. 
Fig.    262.      Hypertrophy    of    the    gums    and    alveolar    process.      The    radiograph    show.-    no    irritant 
cause   for   the   condition,    and    none    was  found    otherwise. 


My  readers  are  by  this  time  acquainted  with  the 

Tig.  261.  appearance  of  normal  alveolar  process  and  jaw  bone. 

Fig.   261    shows   what   I  believe  to  be   an   osteoma. 

The  patient  would  not  consent  to  the  removal  of  tissue  for  microscopical 

examination.     The  radiograph  shows  only  that  the  bone  is  diseased.    The 

exact  nature  of  the  disease  must  be  determined  by  the  microscope. 

Case :    Enlargement  of  the  gums  about  the  upper 
Tig.  262.  anterior    teeth,    causing    considerable    disfigurement. 

Fig.  262  shows  what  was  thought  to  be  hyper- 
trophy of  the  gum  tissue  and  alveolar  tissue.  [Microscopic  examination 
verified  the  diagnosis.  The  teeth  and  the  hypertrophied  tissue  were  re- 
moved. 

At  the  age  of  thirteen  a  permanent  lateral  had 

Tig.  263.  failed   to  erupt.     A   radiograph   was  made  to  learn 

whether  or  not  it  was  present  in  the  jaw.     Fig.  263: 

shows  the  permanent  lateral,  and  shows  also  why  it  has  not  erupted.     In 


228  DENTAL   RADIOGRAPHY 

the  path  of  eruption  is  seen  what   I  believe  to  be  an  "epithelial,  com- 
posite"* odontoma. 

Odontomata  sometimes  assume  considerable  size.  To  be  abso- 
lutely sure  in  diagnosis,  and  to  be  certain  of  their  complete  removal,  the 
radiograph  should  be  used. 


'.:>.      The   upper   arrow    points    to    the   permanent   lateral    incisor.      The   lower    arrow    points 
to  an   odontoma.      (Radiograph   by    Flint,   of   Pittsburgh.) 


""The    case     illustrated     in     Fig.     264    presents 
j jg.  264.  many    interesting   features    from    the    standpoint   of 

diagnosis  and  treatment.  The  patient  was  a  woman 
about  thirty-five  years  of  age,  who  suffered  for  a  number  of  years  from 
pains  in  the  ear  and  the  tonsilar  region,  as  well  as  from  difficulty  in  masti- 
cation and  deglutition,  while  her  general  health  had  deteriorated  to  such 
an  extent  that  she  became  very  anemic,  having  suffered  from  malnutrition 
due,  no  doubt,  to  imperfect  mastication  and  the  absorption  of  pus  prod- 
ucts.  In  this  condition  she  was  referred  to  the  extracting  specialist  who 
was  unable,  from  the  ankylosis  present,  to  arrive  at  any  definite  conclusion 
as  to  the  possibility  of  an  impacted  tooth  which  was  suspected,  while  the 
only  evidence  that  pointed  in  this  direction  was  a  free  discharge  of  pus 
through  a  fistulous  opening  in  the  soft  tissues  over  the  third  molar  region 
of  the  right  inferior  maxillary. 

"She  was  therefore  referred  to  the  radiographer  when  the  true  con- 
dition, as  shown  in  Fig.  264.  was  revealed.  The  necessity  for  removing 
the  displaced  second  molar,  as  well  as  the  odontoma,  presented  a  situation 
which  was  not  a  pleasing  one  to  contemplate.  The  patient,  as  well  as  her 
friends,  were  informed  of  the  probability  of  fracturing  the  mandible  in 
the  endeavor  to  remove  the  molar  and  the  dental  tumor,  which  together 


♦Barrett  "Oral   Pathology  and   Practin  " 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY    229 


Fig.    264.     A    large    composite    odontoma.       (Radiograph    by    Chene,    of    Detroit.) 

occupied  almost  the  entire  body  of  the  mandible  at  the  angle  of  the 
ramus.  Under  a  general  anesthetic  of  nitrous  oxide  and  oxygen,  which  was 
followed  by  ether,  the  tumor  was  removed,  as  was  also  the  impacted  molar, 
without  any  great  difficulty,  but  when  the  circumscribed  bony  structure 
about  the  molar  was  drilled  and  chiseled  sufficiently  to  permit  of  an  ele- 
vator passing  under  one  corner  of  it  and  pressure  applied,  the  expected 
happened,  and  a  break  in  the  body  of  the  mandible  occurred.  This  acci- 
dent was  of  no  serious  consequence,  however,  for  under  an  occipito- 
mental bandage,  which  a  few  days  later  was  reinforced  by  wire  fixation, 
the  fracture  healed  and  the  case  proceeded  to  an  uneventful  and  speedy 
recovery,  with  complete  restoration  of  health.  The  odontoma  was  of 
composite  structure,  the  central  part  being  made  up  of  what  may  have 
been  the  third  molar,  about  which  were  arranged  concentric  layers  of 
cementum,  and  probably  some  compact  bony  structures." 

For  the  report  of  this  case  I  am  indebted  to  Dr.  Don  M.  Graham,  of 
Detroit.  Mich. 


230  DENTAL   RADIOGRAPHY 

45.    Co  Observe  Anomalous  Conditions  Such  as  the  Tusion  of  the  Roots  of 
two  teeth  for  example. 

Case :   Child  about  twelve.   The  crowns  of  two  of 
Tig.  2b$.  the   lower   incisors  seemed   fused  together.     To  ac- 

complish regulation  of  the  teeth  it  became  expedient 
in  the  opinion  of  the  operator  handling  the  case  to  extract  one  of  the 


Fig.    265.      Show?   that   the   two   lower   incisors    are    not    fused   together. 

incisors.  The  choice  of  the  tooth  to  extract  fell  to  one  of  the  two  which 
seemed  fused  together.  The  question  arose :  "Are  the  roots  of  the  teeth 
fused  also?"  A  radiograph  (Fig.  265)  shows  they  arc  not.  It  shows 
further  that  the  crowns  arc  not  fused  cither,  though,  let  me  admit,  I 
shared  in  the  mistake  of  the  man  who  referred  the  case  thinking  they 
were;  and  failed,  as  he  had,  in  an  attempt  to  pass  a  ligature  between 
them.  It  was  not  until  I  had  the  radiograph  before  me,  showing  me  that 
1  was  not  attempting  the  impossible,  that  I  succeeded  in  getting  a  silk 
ligature  between  the  teeth.  One  of  the  teeth  was  slightly  malformed; 
they  wen-  almost  mortised  together  in  consequence,  and  in  contact  from 
the  incisal  edge  to  beneath  the  gum  margin. 

ond  and  third  molars  are  sometimes  fused  together.  I  recall  hav- 
ing extracted  the  upper  second  and  third  molars  in  an  effort  to  remove 
the  third,  the  roots  of  the  two  teeth  having  been  coalesced.  Had  I  used 
radiographs,  and  known  the  condition  which  existed,  T  might  have  con- 
served the  third  molar,  and  so  saved  the  second  molar,  which  latter  was 
a  useful  tooth.  (  )r,  had  it  been  necessary  to  remove  the  teeth,  I  might 
have  saved  my  patient  considerable  pain  by  a  more  inclusive  use  of  my 
local  anesthetic. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     231 

46.    Co  Observe  the  Location  and  extent  of  a  necrotic  or  Carious  Condition 

of  Bone. 

This  radiograph  is  of  a  case  of  arsenical  necrosis. 

Tig.  266.  which    would    not   yield   to   the   usual    treatment   of 

curettement  and  drug  stimulation.    The  arrow  point? 

to  the  line  of  demarcation,  below  which  can  be  seen  the  sequestrum.    The 

case  recovered  promptly  upon  removal  of  the  sequestrum. 


The  arrow  points  to   the   line  of  demarcation,   beneath    which   can   be   seen   the 
sequestrum. 


Case:  Necrosis  of  the  lower  jaw,  caused  by  an 
Tigs.  2t>~  and  2&S.  abscessed  tooth.  The  patient  suffered  for  a  year 
from  recurrence  of  an  abscess  in  the  lower  jaw.  Dur- 
ing this  time  he  made  several  changes  from  one  dentist  or  physician  to 
another.  At  the  time  the  case  came  under  the  care  of  Dr.  Gilmer,  of 
Chicago,  the  symptoms  were  alarming.  There  were  two  external  pus 
sinuses  along  the  lower  border  of  the  mandible  in  the  bicuspid  region. 
The  patient  had  been  unable  to  lie  down  for  a  period  of  ten  days  because 
of  the  intense  pain  which  resulted  from  assuming  a  recumbent  position. 
The  body  temperature  rose  and  fell  by  turns.  Stupor  and  coma  occurred. 
A  radiograph  of  the  case  (Fig.  267)  shows  a  sequestrum  about  the 
size  of  the  first  joint  of  the  thumb  along  the  lower  border  of  the  mandible 
in  the  bicuspid  and  cuspid  region.  The  line  of  demarcation  can  be  seen 
fairly  well  in  the  plate  before  me.  I  regret  that  I  was  unable  to  obtain  a 
good  print  of  this  case.  The  negative  was  an  excellent  one,  but  the 
photographer  who  made  the  print  from  it  did  poor  work. 

The  operation,  done  by  Dr.  Gilmer,  of  Chicago,  was  as  follows :  An 
external  incision  was  made  along  the  lower  border  of  the  mandible  in  the 
region  of  the  sequestrum,  and  the  sequestrum  removed  through  it.  The 
bone  was  curetted,  a  drainage  tube  inserted,  and  the  incision  sewed  up. 
The  first  bicuspid  and  cuspid  were  extracted. 


-  - 


DEXT.IL  radiography 


Fig.    2C7.      The    arrow    points   to    a    sequestrum    about    the    size    of   the    first    joint    of    the    thumb. 
(Radiograph   by    Porter,   of   Chicago.) 


68.     Same  as    Fi«.    867,    with   the   line   of    demarcation    outlined    to    enable    th<-    readei    to 
observe  it  better  than   in    Fig.   267. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     233 


Fig.   269.     EE,   ends  of  overlapping  bone. 


Had  the  operator  not  had  a  radiograph  to  guide  him  in  his  work  he 
could  not  possibly  have  performed  the  operation  as  quickly,  thoroughly, 
and  intelligently  as  he  did,  for  he  would  not  have  known  just  where,  and 
just  how  big,  the  sequestrum  was. 

A  case  of  phosphor  necrosis  of  the  lower  jaw 
Ti<J.  269.  several  years  after  removal  of  the  sequestrum.    The 

jaw  is  in  two  parts,  with  the  ends  overlapping. 

A  carious  condition  of  the  alveolar  process  and 
Tig.  270.  superior  maxillary  bone,  caused  by  the  retention  of  a 

piece  of  tooth  root  above  the  dummies  of  a  bridge. 
Curettement  and  stimulation  with  drugs  might,  or  might  not,  be  necessary 
in  this  case,  but  it  is  probable  that  the  carious  bone  will  regain  normal 
health  and  vitality  upon  removal  of  the  direct  cause  of  the  caries — the  bit 
of  tooth  root. 


234  DENTAL   RADIOGRAPHY 

47.    to  Diagnose  Antral  empyema. 

This  radiograph  was  made  from  a  dry  skull.     It 
fig.  271.  shows  the  following:     The  frontal  sinuses  AA,  the 

orbits  BB,  ethmoid  cells  CC,  the  nasal  cavity  DD, 
and  the  maxillary  sinuses  EF.  The  sinus  E  is  filled  with  lead  shot,  the 
sinus  F  has  a  molar  tooth  in  it.  The  picture  is  printed  to  give  one  an 
opportunity  to  study  the  "landmarks"  of  such  a  radiograph,  and  so  enable 
one  to  interpret  the  coming  pictures  more  readily. 


Fig.    270.      Carious    condition    of    the    alveolar    process    and    bone,    caused    by    a    piece    of    tooth 
root    above    the    dummies    of    a    bridge.       (Radiograph    by    Lewis.) 

To  observe  pus  in  the  antrum  it  is  necessary  to 
fig.  272.  make  a  radiograph  of  both  antra,  that  they  may  be 

compared.  In  Fig.  272  the  antrum  A  is  filled  with 
pus,  the  antrum  B  is  healthy.  It  must  be  borne  in  mind  that  the  radio- 
graph alone  does  not  demonstrate  to  us  the  presence  of  pus  in  the  antrum. 
It  shows  us  only  that  there  is  something  in  the  antrum.  The  appearance 
of  the  radiograph  would  be  about  the  same,  whether  that  something  were 
pus  or  a  soft,  tumorous  growth.  Such  a  radiograph  as  Fig.  272  will  show 
whether  the  disease  is  confined  to  the  antrum  or  involves  the  ethmoidal 
cells  and  frontal  sinuses.    In  this  case  the  disease  exists  only  in  the  antrum. 

Cloudiness  of  the  antrum  A   indicates  a  patho- 

Tigs.  273  and  274.       logical    condition.      In    Fig.    273    the    arrows    point 

to  a  dark  shadow,  which  is  an  impacted  upper  third 

molar  tooth.     Fig.  274  is  a  lateral  view  of  tin-  same  rase,  and  shows  the 

impacted  tooth  clearly.     Extraction  of  the  tooth  effected  an  immediate 

cure.     (This  case  was  one  in  the  practice  of  Dr.  Cryer.) 

4$.    Co  Observe  the  Size,  Shape  and  Location  of  the  Antrum,  a$  an  Aid  in 

Opening  into  Tt. 

I  Inless  a  pus-filled  antrum  is  opened  at  its  low- 
Tig.  275.  point,    it    cannot    be    perfectly    drained.      Unless 
it    i-    perfectly    drained    the    operation    cannot    result 


THE  USES  <>/■'  THE  RADIOGRAPH  IN  DENTISTRY     235 


Fig.    271.      Radiograph    of    a    dry    skull.      One    antrum    is    filled    with    lead    shot,    the    other    lias 
a    molar    tooth    in    it.      This    radiograph    is    clearer    than    one    made    from    the    living    subject    be- 
cause   there   were   no   soft    part.-   or   circulating    blood   to    blot    out    detail. 


in  a  permanent  cure.  The  size,  shape  and  location  of  the  antrum  can 
best  be  observed  stereopticallv.  Often,  however,  a  good  idea  of  its  size, 
shape  and  location  can  be  obtained  from  a  radiograph,  like  Fig.  276, 
for  example.    Radiographs  of  the  antrum  made  on  films  held  in  the  mouth 


23<  • 


DEXTAL   RADIOGRAPHY 


A.    antrum     with    \>u< 


B,    healthy    antrum. 
Louis.) 


(Radiograph    by    Carman,    of    St. 


are  very  misleading  and  confusing,  as  witnessed  in  Fig.  275,  which  was 
made  on  a  film  held  in  the  mouth,  and  is  of  the  antrum  filled  with  lead 
shot — illustrated  in  Fig.  271. 

The  dots  outline  a  very  large  antrum.  An  open- 
fig.  276.  ing  made  at  the  favorite  site  for  opening  into  the 
antrum  through  the  mouth,  above  their  apices,  be- 
tween the  second  bicuspid  and  first  molar  (the  first  molar  has  been  ex- 
tracted;, would  not  puncture  this  antrum  at  its  lowest  point.  The  root 
of  the  second  molar  seems  to  penetrate  the  antrum.  Whether  it  actually 
penetrates  the  floor  of  the  antrum  or  not  I  cannot  say  definitely,  because 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     237 


Fig.    273.      A,    diseased    antrum.      The    shadow    pointed    to    by    the    arrows    is    an    impacted    third 
molar.      B,    healthy   antrum,    CC,    turbinate   bones,    EE,   very   small    frontal    sinuses.      (Radiograph 

by    Pfahler    of    Philadelphia.) 


of  the  lack  of  perspective  in  the  radiograph.  I  am  inclined  to  think,  how- 
ever, that  it  does  not — the  lower  part  of  the  antrum  and  the  end  of  the 
root  overlap,  the  tooth  root  passing  to  the  lingual  of  the  antrum. 

Because  of  its  unusual  size  the  lower  part  of  the  antrum  was  thought 
to  contain  a  malignant  growth.  Dr.  Oyer  rejected  this  interpretation, 
saying  that  the  antrum  must  have  been  of  the  size  shown  in  the  radio- 
graph before  the  formation  of  the  second  and  third  molars,  and  that  the 
large  antrum  was  responsible  for  the  pinched-together  condition  of  their 


238 


DENTAL   RADIOGRAPHY 


Fig.    274.      Lateral    view    of   the   same   case    illustrated    in    Fig.    273.      This    radiograph    shows    the 
impacted   tooth  clearly.      (Radiograph   by    Pfahler   of    Philadelphia.) 


roots.  lie  theorized  further,  accounting  for  the  pain  the  patient  suffered 
by  surmising  that  the  pinched  condition  of  the  roots  of  the  third  molar 
was  causing  pressure  on  the  dental  pulp.  In  his  description  of  the  case 
Dr.  Cryer  does  not  mention  the  faulty  canal  filling  in  the  second  molar 
as  a  possible  cause  for  the  pain.  Both  molar  teeth  were  extracted  and 
the  patient  was  freed  from  neuralgia. 

4Q.  to  Locate  Toreifln  Bodies,  Such  as  tooth  Roots  or  Broaches,  in  the  Antrum. 

Fig.  2jj  shows  a  piece  of  tooth  root  in  the  an- 

TiflS.  277  and  27$.       trum.     It  is  a  portion  <>i  the  second  bicuspid,  which 

had  been  extracted  (  ?)  about  a  week  previous  to  the 

time  when  the  patient  presented  to  Dr.  Virgil  Loeb  for  treatment.     The 


THE  USES  OF   THE  RADIOGRAPH  IN  DENTISTRY     239 


Fig.   27").     Antrum   tilled   with  lead  shot.     The   same   as    Fig.   271. 


Fig.    276.     The   dots    outline    a   very   large    antrum.     A    septum    is    seen    in    this    antrum    dividing 
it  into  two  parts.     The  arrows  point  to  the  lower  part.     (Radiograph  by   Pfahler,  of  Philadelphia.) 


240 


PF.XTAL   RADIOGRAPHY 


Fig.  877. 


The  arrows  point  to  a  piece  of  tooth  root  in   the  antrum, 
of   St.   Louis.) 


(Radiograph   by   Carman, 


first  molar  was  extracted,  an  opening  made  into  the  antrum  through  one 
of  its  alveoli,  and  the  piece  of  root  removed.  The  object  of  the  operation 
to  remove  the  piece  of  tooth  root  from  the  antrum.  This  was  accom- 
plished. And  again  let  me  repeat  what  I  have  said  before:  An  operator 
may  make  a  greater  mistake  than  that  of  the  extraction  of  a  tooth — he 
may  conserve  the  tooth  at  the  expense  of  the  health  and  happiness  of  the 
patient.  Conservative  dentistry  often,  all  too  often,  means  conservation 
•  .I*  disease. 


THE  USES  o/:  THE  RADIOGRAPH  IN  DEXTISTRY    241 


Fig.    278.     Same    case    as    Fi 


277    after    removal    of    the   piece   of    tooth    root.       (Radiograph    by 
Carman,   of  St.   Louis.) 


Dr.    Cryer    says    of    Fig.    279:      "It    is    mark 
Ti<j.  279.  from    a    patient    who    had    trouble    in    the    maxil- 

lary sinus  for  some  time.  The  picture  clemon- 
strated  that  a  piece  of  rubber  tubing,  which  had  been  used  for  drainage, 
had  slipped  into  the  antrum  and  become  lodged  in  the  region  of  the 
ostium  maxillare.  After  its  removal  and  a  brief  treatment,  the  part 
became  well." 


242 


DENTAL   RAD10CRAPIIY 


Fig.    279.     The    arrows    point    to    a    piece    of    rubber    tubing    in    the    antrum. 

I'aneoast.    of    Philadelphia.) 


(Radiograph    by 


so.    Co  Observe  Gases  of  Euxation  Before  and  After  Reduction. 

The  symptoms  of  dislocation  of  the  condyle 
Tigs.  280  and  281.  from  the  glenoid  fossa  are  so  characteristic  that,  it 
seems  to  me,  even  the  most  inexperienced  should 
recognize  them  with  ease.  It  is  a  fact,  however,  that  the  case  illustrated 
in  Figs.  280  and  281  was  diagnosed  dislocation,  because  I  presume  the 
patient  could  not  get  the  anterior  teeth  together.  The  radiographs  show 
two  fractures.  Fig.  280  mar  the  angle,  and  Fig.  281,  of  the  other  side  of 
the  jaw,  in  the  second  bicuspid  region. 


Tifl.    282. 


living  subject. 


Tin's  radiograph  is  by  Tousey,  of  New  York 
( 'itv,  and  is  one  of  the  clearest  radiographs  of  the 
temporo-mandibular  articulation  ever  made  from  a 


THE  USES  OE  THE  RADIOGRAPH  IN  DENTISTRY     243 


Fig.   280.     The  arrows   point   to  a    fracture  of   the  jaw   in   the   region  of  the  angle.      (Radiograph 

by    Ccle    and    Raper.) 


Fig.   281.     The   arrows  point   to   a   fracture   of  the  lower   jaw  just   posterior   to   the   second    bicus- 
pid.     The    opposite    side    of    the    same    jaw    radiographed    in    Fig.     280.       (Radiograph    by    Cole 

and    Raper.) 


244 


DENTAL  RADIOGRAPHY 


Fig. 


Ilent    radiograph    of    the    temporo-mandibular    articulation.      Made    from 
subject.      (Radiograph    by    Tousey,    of    New    York    City.) 


Case :      Dislocation    of    the    condyle    from    the 
Tigs.  283  and  284.       glenoid   fossa.     Fig.  283   shows   the   condyle  A  an- 
terior to  the  emincntia  articularis  B.    Fig.  284  of  the 
same  case  after  reduction.    While  it  fails  to  show  the  condyle  itself  clearly, 
it  shows  the  neck  of  the  condyle  and  demonstrates  that,  in  this  picture,  the 
condyle  A  is  on  the  other  side  of  the  emincntia  articularis  B. 

si.    In  Gases  of  fracture  of  the  3aw. 

Fracture  of  the  jaw  is  almost  always  accompanied  by  such  a  great 
deal  of  swelling  and  induration  that  digital  and  ocular  examination 
arc  highly  unsatisfactory.  The  operator  who  treats  a  fracture  should 
know  just  where  and  what  kind  of  a  fracture  he  is  dealing  with.  If  there 
he  displacement  of  the  fragments,  he  must  know  how  much,  and  in  what 
direction,  the  displacement  occurs,  in  ordef  that  he  may  properly  readjust 
the  parts.    This  knowledge  can  be  gained  only  by  the  use  of  radiographs — 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     245 


Fig.     2S3.      Dislocation    of    the    condyle    from    the    glenoid    fossa.       A,    condyle, 
articularis.       (Radiograph    by    Cole    and    Raper.) 


B,    eminentia 


stereoptic  radiographs  in  cases  where  there  is  considerable  displacement 
of  the  fragments. 

Fracture   at   the   symphysis.      The   appliance   on 
the  teeth  is  being  used  as  a  splint. 


Tifl.  285. 


Case   in  the   practice   of   Dr.   Oyer.      Fig.   286 

?i8$.  2$6  and  2$7.       shows  a  fracture  of  the  mandible  at  the  angle.     The 

body  of  the  jaw  is  displaced  downward.     Fig.  287  is 

of  the  same  case  after  reduction  and  adjustment  of  an  interdental  splint. 

While  the  apposition  of  the  fractured  ends  is  not  perfect  yet,  there  is  a 


-4" 


DRXTAL   RADIOGRAPHY 


* 

l 

1 

-  ** '  ^B 

i    X 

" 

Fig.    284.      Same    as    Fig.    283    after    reduction    of    the    dislocation.      A,    condyle.       B,    eminentia 
articularis.      (Radiograph    by    Cole    and    Raper.) 


very  great  improvement  over  the  condition  showed  in  Fig.  286,  and  I  be- 
lieve the  apposition  to  be  as  near  perfection  as  human  ingenuity  is  capable 
of  carrying  it. 

Just  when  to  remove  a  splint  and  bandage  from  a  fracture  case  is 
always  a  problem.  The  splint  shown  in  big.  287  was  removed  at  the  end 
of  the  eighth  week.  I  Jr.  Loeb,  of  St.  Louis,  Mo.,  states  that  radiographs 
are  a  great  aid  in  determining  just  when  to  remove  splints. 


A  double,  comminuted  fracture  of  the  mandible 
Tig.  2$$.  four  months  after  the  accident.     The  bone  in  the 

region  of  the  fracture  is  necrotic. 


THE  USES  OE   THE  RADIOGRAPH  IN  DENTISTRY     247 

52.    Tn  Cases  of  Ankylosis  of  the  temporomandibular  Articulation  or  the 
Joint  formed  by  the  tooth  in  the  Saw. 

The  radiograph  is  of  value  in  cases  of  ankylosis  to  observe  the  cause 
of  the  ankylosis. 

Case :    A  miner  who  had  sustained  a  traumatism 

Tig.  2$<>.  resulting  in  ankylosis.    The  ankylosis  had  existed  for 

several  months  at  the  time  Fig.  289  was  made.    The 

dots  outline  the  missing  parts,  i.e.,  the  anterior  border  of  the  ramus  and 


Fig.  285.     Fracture  of  the  mandible  at  t lie  symphysis,      (Radiograph  by   Blum,  of  New  York  City. ) 

the  coronoid  process.  The  disease  of  the  bone  could  not  have  failed  to 
affect  the  temporal  and  masseter  muscles.  It  [s  my  belief  that  in  this  case 
the  true  muscular  tissue  was  destroyed  and  replaced  with  cicatricial  tissue, 
which  condition  caused  a  false  ankylosis.  I  consulted  two  surgeons,  but 
neither  was  able  to  suggest  a  corrective  operation. 

An  orthodontist  was  unable  to  move  a  tooth  into  proper  occlusion. 
He  referred  the  case  to  me,  thinking  perhaps  the  presence  of  a  super- 
numerary tooth  body  was  responsible  for  the  immobility  of  the  tooth.  A 
radiograph  demonstrated  the  absence  of  any  such  body,  and  showed  that 
the  tooth  had  practically  no  peridental  membrane  at  all.  There  was  a 
condition  of  partial  ankylosis,  to  overcome  which  it  was  necessary  for  the 
orthodontist  to  reinforce  his  anchorage  and  exert  more  force  on  the  re- 
fractory tooth.  I  do  not  print  a  radiograph  of  this  case  because  of  the 
great  difficulty  of  showing  the  peridental  membrane,  or  the  absence  of  it, 
in  a  half  tone. 

S3,    to  Observe  the  Tield  of  Operation  before  and  after  Resection  of  the  mandible. 

Resection  of  the  mandible  is  a  difficult,  radical  operation,  and  one 
which  has  been  performed  comparatively  few  times.  With  the  excep- 
tion of  Dr.  Ballin  (Items  of  Interest,  June.  1908).  operators  who  have 
done  this  operation  have  not,  so  far  as  I  am  able  to  learn,  availed  them- 


248 


i > i:\r.ii.  radiography 


Fig.   28r,. 


Fracture   at    the   angle   of    the    mandible.      Displacement   of    fractured    ends 
gra;  h    by    Pancoast,    of    Philadelphia.) 


(Radio- 


Fig.     280     aft' r     i_«  «l»i<-ti.»ii     an rl     ad juMin.  nl 

(Radiograph   by    Pancoast,   of    Philadelphia.) 


dental    splint. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY    249 


Fig.    288.     Double    comminuted    fracture    of    the    mandible.       That    the    reader    may    understand 

the    picture,    observe    the    following:     A,    zygomatic    arch;    B,    sigmoid    notch;    C,    upper    part    of 

ramus;    D,    one    fracture;    E,    the    other    fracture;    F,    fragment    of    bone    between    fractures. 


selves  of  the  assistance  which  good  radiographs  of  the  case  would  have 
rendered.  Resection  of  the  mandible  might  become  necessary  as  a  re- 
sult of  an  existing  pathological  condition  of  the  bone,  or  it  might  be  done 
to  correct  a  bad  case  of  prognathism.  For  whatever  reason  the  operation 
may  be  done,  the  operation  itself  is  the  same,  in  that  a  piece  of  the  man- 
dible is  removed.  Consider  the  operation  for  prognathism,  for  example : 
A  piece  of  the  body  of  the  mandible  from  each  side  is  cut  out  and  re- 
moved. The  anterior  part  is  then  forced  back  and  the  cut  ends  of  the 
bone  (four  of  them)  wired  into  apposition.  That  anti-  and  post-operative 
radiographs  of  such  a  case  would  be  of  value  is  apparent. 

54.  Tn  Jill  Cases  of  facial  neuralgia  with  an  Obscure  etiology. 
Cases  of  facial  neuralgia  with  an  obscure  etiology,  the  exciting  cause 
for  which  was  disclosed  by  the  radiograph,  have  already  been  described 
under  more  specific  headings — Figs.  159,  164,  176,  177,  170.  --4.  246. 
247,  248,  249,  250,  264,  and  others.  Until  the  exciting  cause  is  found 
when  it  then  receives  a  more  specific  name,  any  dental  pain  is  likely  to 
be  referred  to  as  neuralgia. 


250  DENTAL   RADIOGRAPHY 

When  making  radiographs  to  learn  the  cause  of  trifacial  neuralgia, 
it  is  expedient  usually  to  make  a  large  8  x  10  picture  of  the  affected  side. 
This  radiograph  can  then  be  studied  and,  if  some  lesion  is  discovered, 
another  radiograph  of  the  particular  region  of  the  lesion  made  on  a  small 
film.  The  second  radiograph,  on  the  film,  will  be  clearer  than  the  one  on 
the  plate,  and  will  verify  or  disprove  the  findings  in  the  larger  picture. 


Fig.   289.     The   'lots   outline   the   missing   parts — i.e.,   the   anterior   border   of  the   ramus   and   the 
coronoid   process.      (Radiograph   by  Cole  and   Raper.) 

Case:  Married  woman,  middle  age,  suffered 
Tigs.  290  and  291.  from  pains  in  the  region  of  the  upper  bicuspids.  The 
dentist  could  find  no  lesion  that  might  be  responsible 
for  the  trouble.  A  radiograph  (Fig.  290)  was  made,  but  does  not  show 
the  upper  teeth  clearly.  It  does,  however,  show  a  shadow  in  the  body  of 
the  mandible  in  the  region  of  the  lower  first  molar,  which  tooth  is  missing 
from  the  jaw.  A  radiograph  (Fig.  291)  of  the  region  in  which  the 
shadow  appeared  was  made  on  a  small  film  held  in  the  mouth.  The  film 
was  not  placed  in  exactly  the  proper  position  and,  as  a  result  of  this  mis- 
take, pictures  only  a  part  of  the  lesion.  It  shows  the  crown  of  a  super- 
numerary lower  bicuspid  with  three  supernumerary  bodies  (denticles) 
above  it.  Though  the  lesion  in  the  lower  jaw  was  not  at  the  location  in 
which  pain  occurred,  it  was  doubtless  responsible  for  the  neuralgia. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     251 

The  patient   would  not  submit  to  an  operation.      The  case,   if  not 

operated  upon,  will  probably  progress  to  a  large  dentigerous  cystic  tumor. 
Evidence  of  this  can  already  be  noticed  in  Fig.  290  by  the  lack  of  normal 
density  of  the  surrounding  bone. 


Fig.    290. 


The    arrow    points    to    a    shadow    in    the   body    of    the    mandible    in    the    region    of    the 
lower  first   bicuspid.      (Radiograph   by   A.    M.   Cole,    of   Indianapolis.) 


Case:     Married  woman,  physician's  wife,  about 
Tig.  292.  fort)r-eight  years  old.  had  suffered  for  twenty-five 

or  thirty  years  with  attacks  of  neuralgia  occurring 
four  or  five  times  a  year,  each  attack  lasting  for  several  days.  None  save 
dental  operations  were  performed,  though  she  received  palliative  treat- 
ment for  ear,  mastoid  cells  and  antrum  trouble.  Xo  treatment  gave  relief. 
She  left  her  home  in  Indiana  and  spent  one  winter  in  South  Carolina, 
hoping  the  milder  climate  would  ward  off  the  attacks  of  pain,  but  this 
proved  futile.     At  no  time  did  her  temperature  rise  above  normal,  prov- 


252  DENTAL   RADIOGRAPHY 

ing.  or  seeming  to  prove,  that  whatever  the  irritation,  there  was  little  or 
no  suppuration  attending  it.  A  radiograph  (Fig.  292)  was  finally  made, 
and  showed  an  impacted  upper  third  molar.  This  tooth  was  removed, 
and  since  then,  now  over  four  years  ago,  she  has  not  had  a  single  attack 
of  neuralgia. 

Attention  is  called  to  the  fact  that  up  to  the  time  of  making  the  radio- 
graph this  was  a  typical  case  of  idiopathic  facial  neuralgia. 


Fig.  291.  The  same  case  as  Fig.  290.  A  radiograph  of  the  upper  part  of  "the  shadow."  It 
shows  the  crown  of  a  supernumerary  bicuspid  with  three  denticles  above  it.  The  white  spot 
at  the  apex  of  the  second  bicuspid  is  caused  by  an  air  "bell"  attaching  itself  to  the  film  in  that 
region  at  the  time  it   was  in  the   developing  solution.     (Radiograph  by  A.  M,  Cole,  of  Indianapolis.) 


ss.    Co  Observe  the  Inferior  Dental  Canal. 

Often,  but  not  always,  we  are  able  to  radiograph  the  inferior  dental 
canal.  (See  Fig.  190.)  To  the  man  contemplating  resection  of  the  in- 
ferior dental  nerve  anywhere  throughout  its  course  in  this  canal  a  radio- 
graph showing  the  location  of  the  canal  would  be  of  value. 

Dr.  Virgil  Loeb,  of  St.  Louis,  reports  a  case  of  anesthesia  of  the 
lower  lip.  and  that  part  of  the  face  011  one  side  which  receives  its  nerve 
supply  from  the  nerves  passing  through  the  mental  foramen.  The  anes- 
thesia followed  the  extraction  of  a  lower  third  molar.  A  radiograph  of 
the  case  showed  that  the  roots  of  the  third  molar  had  penetrated  the  in- 
ferior dental  canal.  Knowing  this,  it  was  deduced  that,  at  the  time  of 
extraction,  the  inferior  dental  nerve  had  been  stretched,  and  a  few  fibers 
torn  at  the  mental  foramen.  Lately  I  have  personally  observed  such  a 
case.  I  do  not  print  radiographs  of  either  Dr.  Loeb's  or  my  own  case, 
because  they  are  not  clear  enough  to  permit  of  good  half-tone  reproduc- 
tion. Such  cases  as  the  ones  now  under  consideration  recover  slowly,  the 
time  required  varying  from  one  to  several  months.  Treatment  with  the 
high-frequency  current  maw  or  may  not,  hasten  recovery  slightly.  Though 
slow,  complete  recovery  may  be  expected. 


THE  USES  <>/■'  THE  RADIOGRAPH  IN  DENTISTRY     253 

Immediately  after  the  filling  of  the  canals  of  a  lower  second  molar  a 
patient  suffered  most  severe  pain  in  the  region  of  the  filled  tooth.  A 
radiograph  was  made  and  showed  the  canal  filling  penetrating  the  apical 
foramen  of  the  distal  root,  projecting  into  the  inferior  dental  canal,  and 


Fig.   293.     The  arrow  points  to  an  impacted  upper,   third  molar,  the  cause   of  "idiopathic"   neu- 
ralgia,   from   which   the   patient   had   suffered   recurrently    for   from   between   twenty-five   to   thirty 
years.      (Radiograph  by  A.  M.   Cole,  of  Indianapolis.) 


doubtless  pressing  the  inferior  dental  nerve.  An  effort  to  remove  the 
canal  filling  met  with  failure,  and  the  tooth  was  extracted  to  relieve  the 
patient  of  the  intense  pain.  Again  I  do  not  print  radiographs  of  the  case 
because  the  prints  are  not  sufficiently  clear  to  permit  of  good  half-tone 
reproductions. 

56.  Tn  eases  of  Eudwig's  Angina. 
Angina  is  defined  in  Dorland's  Medical  Dictionary  as  "any  disease  or 
symptom  characterized  by  spasmodic  suffocative  attacks" :  Ludwig's 
angina  as  "purulent  inflammation  seated  around  the  submaxillary  gland." 
Whenever  there  is  a  pus  sinus  opening  on  the  neck  in  the  region  of  the 
submaxillary  gland,  the  patient  is  said  to  have  Ludwig's  angina.  This  is 
the  popular  application  of  the  term,  and  it  seems  to  the  writer  unfor- 


2>l 


DENTAL    RADIOGRAPHY 


Fig.   293.      Photograph   of   a  case   of   so-called   Ludwig's  angina.      Also   a   radiograph   of   the  case 
showing  an   abscess   of   the   first  permanent   molar.      The   fistulous  tract  cannot   be   seen. 


tunate,  for  there  is  seldom  angina — i.e.,  suffocative  attacks — in  these  cases 
of  suppuration  of  the  neck. 

Fig.  2<j3  is  a  photograph  of  a  case  of  so-called 

Tig.  293.  Ludwig's  angina  occurring  in   a  child  ten  years  of 

age.      The    accompanying    radiograph    of    this    case 

-hows  an  abscessed  lower  first  molar,  which  was  responsible  for  the  sinus 

on  the  neck.    The  arrow  points  to  a  notch  in  the  lower  border  of  the  body 

of   the  mandible.     Extraction  of  the  lower   first  molar  and   curettement 

of  the  alveoli  was  all  that  was  necessary  to  effect  a  cure  in  this  case.    Had 

the  patient  been  older,  or  not  so  vigorously  healthful,  the  slightly  necrotic 

area  pointed  to  by  the  arrow  would  have  required  curettement  through  a 

facial   opening.     The  radiograph  happens  to  demonstrate  the  congenital 

•  nee  of  a  lower  second  bicuspid. 


THE  USES  OE  THE.  RADIOGRAPH  IN  DENTISTRY     255 

Dr.  H.  R.  Sparrevohn,  of  Los  Angeles,  reported  a  case  of  "Ludwig's 
Angina"  in  the  June  number  of  the  Dental  Cosmos,  1910.  The  patient 
was  receiving  hospital  treatment  for  suppuration  of  the  glands  of  the 
neck,  when  Dr.  Sparrevohn  examined  the  case,  had  radiographs  made, 
and  pronounced  the  trouble  due  to  an  impacted  lower  third  molar,  which 
could  be  seen  clearly  in  the  radiograph,  and  in  appearance  was  similar  to 
Fig-  159.  Neither  the  patient  nor  the  attending  physicians  could  be  con- 
vinced that  his  diagnosis  was  correct.  (Had  the  fistula  been  injected 
with  bismuth  paste  and  a  radiograph  made  there  would  have  been  no 
chance  for  dispute.)  Dr.  Sparrevohn  closed  his  report  of  the  case  as  fol- 
lows:  "I  should  be  thankful  to  readers  of  the  Dental  Cosmos  if  they 
would  express  themselves  as  to  the  correctness  of  my  diagnosis.  At  pres- 
ent I  am  much  discredited,  especially  by  the  medical  men  connected  with 
the  case." 

Dr.  Herbert  Mcintosh,  a  physician,  answered  Dr.  Sparrevohn  in 
Dental  Cosmos,  October,  1910.  He  said  in  part:  "I  think  there  can  be 
scarcely  any  doubt  that  the  malposed  molar,  of  which  very  good  radio- 
grams were  presented,  was  the  cause  of  the  serious  symptoms  reported. 
Anyone  who  has  had  experience  in  the  skiagraphing  and  observing  of 
such  cases  would  have  no  hesitation  in  suspecting  dental  irritation  as  the 
origin  of  the  symptoms  reported  in  the  case.  In  general,  the  medical  man 
is  too  apt  to  overlook  the  reflex  irritation  produced  by  the  teeth.  There 
is  evident  need  of  skiagraphy  to  clear  up  these  obscurities  of  diagnosis  in 
conditions  of  the  face  and  cranium.  There  should  likewise  be  a  greater 
readiness  to  admit  the  importance  which  teeth  have  in  producing  patho- 
logical conditions  of  the  tissues." 

I  believe  I  am  safe  in  saying  that  about  all  of  the  cases  of  so-called 
Ludwig's  angina  are  due  to  dental  lesions.  Yet,  referring  to  no  less  than 
a  dozen  medical  dictionaries  and  works  on  the  practice  of  medicine,  I 
find  that  none  of  them  even  mention  the  teeth  as  an  etiological  factor  to 
be  considered.  These  books  state  that  the  disease  is  caused  by  diphtheria, 
erysipelas,  syphilis,  tuberculosis,  and  that  it  occurs  epidermically  and  idio- 
pathically.  It  is  therefore  not  surprising  that  Dr.  Sparrevohn's  diagnosis 
was  discredited. 

As  is  indicated  by  the  remarks  of  Dr.  Mcintosh,  many  medical  men 
are  more  enlightened  than  the  authors  of  the  books  to  which  I  have  re- 
ferred. But,  on  the  other  hand,  many  of  our  brothers  in  the  practice  of 
general  medicine  need  education  along  this  line.  For  example,  a  physi- 
cian of  my  acquaintance,  a  specialist  on  the  treatment  of  tuberculosis, 
treated,  and  treated  without  benefiting,  a  case  quite  similar  in  appearance 
to  Fig.  293,  giving  the  usual  anti-tubercular  treatment,  including  the  ad- 
ministration of  bacterine.     The  patient's  mouth  had  never  been  examined 


DENTAL   RADIOGRAPHY 

by  a  dentist,  and  radiographs  of  the  case  were  not  made,  nor  were  either 
of  these  things  done  after  I  suggested  them,  because  the  physician  thought 
it  so  highly  improbable  that  the  teeth  could  cause  such  a  condition. 

To  illustrate  the  grave  nature  of  the  symptoms  in  some  of  these  cases 
permit  me  to  report  the  following  case : 

Young  man,  age  twenty-three,  suffered  from  what  was  diagnosed 
pharyngeal  abscess.  Confined  to  the  house  for  a  month,  and  lost  thirty 
pounds.  A  change  of  physicians  brought  in  a  man  on  the  faculty  of  the 
Indiana  Dental  College.  It  became  necessary  to  make  an  external  in- 
cision to  permit  the  escape  of  a  great  quantity  of  pus.  And  let  me  say 
that  because  the  incision  was  made  on  a  line  with,  instead  of  at  right 
angles  to,  the  fibers  of  the  muscle,  the  resultant  scar  is  hardly  noticeable. 
The  writer  was  called  in  consultation.  I  did  not  do  radiographic  work, 
nor  appreciate  its  importance  at  this  time,  or  the  doubt  in  my  mind  as  to 
the  correctness  of  my  diagnosis  might  have  been  eliminated.  The  patient 
could  not  open  the  mouth,  but  instruments  passed  along  the  vestibule  of 
the  mouth  came  in  contact  with  the  corner  of  what  I  suspected  to  be  an 
impacted  lower  third  molar.  The  mouth  was  opened,  the  tooth  found 
and  removed,  and  the  patient  recovered  immediately.  The  impacted  tooth 
was  not  decayed. 

The  radiograph  should  be  used  in  all  such  cases  of  suppuration  about 
the  face  and  neck. 

The  lower  third  molar,   though  not  badly  im- 

Tig.  294.  pacted,  not  malposed  and  not  decayed,  is  abscessed. 

The  abscess  points  externally.     The  fistulous  tract 

cannot  be  seen  in  the  radiograph  because  of  the  slight  destruction  of  bony 

tissue  throughout  its  course. 

57.    Tn  Cases  of  Insomnia,  neurasthenia,  Tnsanity  and  Kindred  nervous  Disorders. 

If  Dr.  Henry  S.  Upson,  of  Cleveland,'  were  a  dentist,  his  assertion 
that  dental  lesions  may,  and  do,  cause  insanity,  would  be  met,  not  alto- 
gether unfairly,  with  the  argument  that,  in  the  practice  of  his  specialty. 
Dr.  Upson  had  developed  a  rare  case  of  myopia,  and  could  no  longer  see 
past  his  especial  field  and  consider  other  etiological  factors.  But  Henry 
S.  Upson  is  not  Henry  S.  Upson,  dentist;  he  is  Henry  S.  Upson,  M.D., 
Professor  of  Diseases  of  the  Nervous  System  at  the  Western  Reserve 
1  'niversity,  and  Attendant  Neurologist  to  the  Lakeside  Hospital,  Cleve- 
land, Ohio. 

The  situation  as  it  stands  to-day  is  this :  Dr.  Upson  claims  that  im- 
pacted teeth  and  chronic  alveolar  abscesses  cause  insomnia,  neurasthenia 
and  insanity.  He  gives  histories  of  radiographically  illustrated  cases, 
which  have  been  cured  by  extraction  of  the  impacted  or  abscessed  teeth, 


THE  USES  OF  THE  RADIOGRAPH  IN  P/iXTISTRY    257 


Fig.     291. 


Alveolar    abscess    pointing    externally.      The    abscess    is    caused    by    the    only    slightly 
impacted   and   not   malposed   lower   third    molar. 


and  he  asks  a  question:  "If  a  diseased  uterus  can  cause  insanity  (and  it 
is  believed  that  it  can),  then  why  not  dental  disease?"  The  nervous  con- 
nection between  the  teeth  and  brain  is  much  more  intimate  than  that  be- 
tween the  uterus  and  the  brain.  No  one  answers  Dr.  Upson's  question, 
and  so  far,  no  one  has  in  any  way  tried  to  prove  Dr.  Upson  wrong  in  his 
belief  that  the  teeth  are  responsible  for  grave  nervous  disorders.  We 
must  then,  in  fairness,  accept  what  he  says  as  the  truth,  until  we  are  able 
to  show  wherein  he  is  mistaken. 

To  give  you  an  idea  of  the  importance  of  dental  lesions  as  a  causa- 


258  DENTAL   RADIOGRAPHY 

tive  factor  in  the  neurosis,  as  promulgated  by  Dr.  Upson,  I  quote  from 
the  doctor's  book,  "Insomnia  and  Nerve  Strain": 

"Of  the  viscera  responsible  for  the  more  obscure  cases  of  nervous 
and  mental  derangement,  I  have  no  hesitation  in  designating  the  teeth  as 
the  most  important.  This  is  not  only  on  account  of  the  common,  almost 
universal  occurrence  of  dental  diseases,  but  because  these  organs  move, 
during  the  period  of  their  development,  through  the  solid  framework  of 
the  jaw.  highly  innervated  and  clothed  by  a  membrane  sensitive  to  im- 
pact and  to  corrosive  toxins." 

That  Dr.  Upson  has  met  with  skepticism  on  the  part  of  his  brother 
practitioners  is  suggested  I  believe  by  the  following,  quoted  again  from 
the  book.  "Insomnia  and  Nerve  Strain": 

"There  seems  to  exist  among  physicians  not  only  a  disregard  but  a 
distinct,  though  mild  dislike  of  the  teeth  as  organs  to  be  reckoned  with 
medically,  they  being,  as  it  were,  an  Ishmael,  not  to  be  admitted  to  their 
pathologic  birthright.  Lauder  Brunton's  essay  on  the  subject  is  too  little 
known  and  heeded,  and  few  such  systematic  attempts  have  been  made  to 
correlate  their  disorders  with  the  suffering  of  the  human  race,  except  for 
the  obvious  phenomena  of  pain.  Ordinary  pain  at  a  distance,  as  head- 
ache or  neuralgia,  due  to  the  teeth,  though  well  known,  is  commonly  dis- 
regarded. Even  the  various  reflex  nervous  phenomena  in  children,  con- 
vulsions, fretfulness,  and  fever,  are  not  now  ascribed  to  the  irritation 
either  of  teething  or  of  dental  caries,  but  to  digestive  disorders.  The 
state  of  recent  opinion,  as  enshrined  in  epigram,  is  that  'The  result  of 
teething  is  nothing  but  teeth.'  " 

My  readers  may  ask  what  has  all  this  to  do  with  dental  radiography? 
Just  this:  the  radiograph  should  be  used  more  extensively,  as  Dr.  Upson 
has  used  it,  in  a  search  for  dental  lesions  in  cases  of  the  various  nerve 
disorders,  for  Dr.  Upson  states  "The  lesions  can  seldom  be  observed  by 
any  means  save  the  use  of  the  X-rays." 

Though  I  would  like  to  print  a  radiograph  and  history  of  all  of  the 
different  neuroses  including  insomnia,  neurasthenia,  mania,  hysteria,  mel- 
ancholia and  dementia,  it  would  hardly  be  in  keeping  with  a  work  of  this, 
kind,  and  I  shall  therefore  give  but  one  case,  which  is  more  or  less  typical. 

Case:  Melancholia  and  insomnia.  "An  unmar- 
Tig.  295.  ried  woman,  twenty-seven  years  old.  a  teacher,  for 

a  year  had  been  profoundly  melancholy  with  intract- 
able insomnia,  delusions  of  various  deadly  sins,  and  entire  hopelessness, 
of  recovery.  Restlessness  was  extreme,  tonic  and  local  uterine  treatment 
of  no  avail.  As  a  last  resort  the  teeth  were  examined.  They  were 
apparently  in  perfect  condition.  A  skiagraph  (Fig.  295)  showed  an  im- 
pacted upper  third  molar  tooth  pressing  against  the  second  molar,  a  con- 


THE  USES  OF  THE  RADIOGRAPH  IN  DEXTISTRY    259 

dition  obviously  capable  of  causing  irritation.  The  symptoms,  in  about 
a  week  after  the  removal  of  the  tooth,  began  to  improve.  Recovery  was 
complete  in  six  or  eight  weeks,  and  has  persisted.  There  had  been  at  no 
time  pain  or  other  localizing  symptoms." 


Fig.    295.      Impacted    upper    third    molar,    causing    melancholia    and    insomnia.       (Radiograph    by 

Lodge,     of     Cleveland. ) 

In  concluding  our  consideration  of  this  subject,  I  quote  from  a  recent 
paper  by  Dr.  Upson  : 

"The  following  is  a  tabulated  statement  of  cases  of  neurasthenia  and 
the  psychoses  seen  in  private  practice  during  about  two  and  a  half  years, 
in  which  skiagraphic  examinations  of  the  teeth  and  jaws  were  made. 
These  results  represent  the  first  stumbling  efforts  in  a  new  and  unknown 
field,  and  so  do  not  adequately  show  what  may  be  accomplished  by  skill 
and  careful  endeavor  along  the  same  line : 

Num-       Opera-       Recov-     Conval-  Im-       Unim-       Xo 

ber  tion  ery  escent      proved     proved     Data 

Manic  depressive  type 11  9  5  ..  2  ..            2 

Dementia  precox 10  8  5  1  ..  2 

Psychosis 4  4  1  2  ..  ..            I 

Insomnia 7  6  2  ..  4 

Neurasthenia   26  15  1  4  6  1           3 


58  42  14           7  12  3           6 

The  following  is  a  separate  statement  of  the  cases  of  impaction  in- 
cluded above  :                                        Xum.  Opera-  Recov-  Conval-  Im-       Unim-       Xo 

ber             tion  ery  escent  proved     proved     Data 

Manic  depressive  type 5           3  2  ..  1 

Dementia  precox 7  5  4  1 

Psychosis 2  2  1  I 

Insomnia 3           2  ..  ..  2 

Neurasthenia   13           9  ..            4  2  I  2 

30  21  7           6  5  1           2 


260 


DEXTAL   RADIOGRAPHY 


5$.    Tn  Gases  of  Periodic  Ijeadacbes. 

Irritation  of  the  trifacial  nerve  may  cause  headache.  The  irritation 
may  be  due  to  such  lesions  as  an  impacted  tooth,  a  chronic  abscess,  or  a 
sementoma,  for  examples. 

"After  the  removal  of  the  malposed  impacted 
Tig.  296.  cuspid  seen  in  Fig.  296,  severe  headaches  which  she 

(the  patient)  had  had  once  or  twice  a  week  for  many 
years  ceased  immediately."* 

Several  cases  similar  to  the  one  cited  above  have  been  reported  in 
recent  dental  literature. 


Fig.  29G  Fig.  297 

Fig.    296.      Malposed    impacted    lower    cuspid,    responsible    for   periodic    headaches.      (Radiograph 

by    Thomas,    of    Cleveland.) 

Fig.  297.     An  impacted  upper  cuspid,  which  caused  blinking  of  the  eyes.      (After 

Dr.    Varney   Barnes.) 


Tig.  297. 


59.    Tn  Cases  of  facial  Gesticulatory  tic.  (Spasmodic  twitching  of  a  Set 
of  Tacial  muscles.) 

"An  impacted  upper  cuspid  which  caused  blink- 
ing of  the  eyes."** 
Dr.  Barnes  also  reported  a  case  of  twitching  of  the  facial  muscles  on 
one  side.  On  the  corresponding  side  two  supernumerary  teeth  were 
found.  I  have  been  unable  to  learn  from  Dr.  Barnes  whether  removal  of 
the  supernumerary  teeth  effected  a  cure.  Dr.  Barnes  agrees  with  Dr. 
Upson  thus  far  at  least:  both  men  are  of  the  opinion  that  impacted 
teeth  may  be  responsible  for  varied  and  grave  nerve  disorders.     Dr.  Up- 


*Dr.  Henry  S.  Upson,  Cleveland,  Ohio. 
**Dr.  Varney  E.  Barnes,  Cleveland,  Ohio. 


THE  USES  OE  THE  RADIOGRAPH  IN  DENTISTRY     261 

son's  treatment  has  always  been  extraction,  while  Dr.  Barnes  advocates 
orthodontic  procedures,  such  as  enlarging  the  dental  arches  and  elevation 
of  the  impacted  tooth. 

to.    Co  flllay  the  Tears  of  a  hypochondriac. 

Every  practitioner  of  dentistry  and  medicine  has  trouble  with  hypo- 
chondriacal patients,  patients  suffering — and  actually  suffering — from 
some  imaginary  ailment.    What  these  patients  need  is  psychic  treatment. 


Fig.    29S.      The   radiograph   demonstrates   the   absence   of   a    piece    of   the   lateral    root   above   the 
lateral   dummy   and   shows   the   canal   of   the   central    and   cuspid   well   filled    and   the   tissues   at 

their  apices  healthy. 


To  be  sympathized  with — or  a  better  way  to  state  it  would  be  to  say  "un- 
derstood"— and  at  the  same  time  shown  that  their  trouble  lies,  not  in  any 
pathologic  lesion,  but  in  faulty  habits  of  thought. 

Case :    Young  lady,  age  about  twenty-three,  com- 
Tifl.  29$.  plained  of  obscure  indefinite  pains  in  the  region  of  a 

bridge  extending  from  central  to  cuspid,  which  pains 
she  declared  were  due  to  an  unremoved  portion  of  the  lateral  incisor  root. 
Having  seen  the  lateral  root  when  it  was  extracted,  and  superintended  the 
treatment  of  the  central  and  cuspid,  and  the  making  of  the  bridge,  and 
knowing  the  patient — in  short,  knowing  the  complete  history  of  the  case — 
I  was  inclined  to  believe  that  the  trouble  with  the  bridge  lay  in  the  diseased 
imagination  of  the  patient.  After  treating  the  case  with  counter-irritants 
once  or  twice,  each  time  conversing  freely  with  the  patient  concerning  her 
symptoms,  and  failing  to  observe  any  clinical  signs  of  a  pathologic  lesion, 
I  became  convinced  that  my  original  surmise  was  correct,  and  that  the 


-   -  DENTAL  RADIOGRAPHY 

teeth  involved  in  the  bridge  were  causing  no  pain.  I  positively  knew 
there  was  not  a  piece  of  the  lateral  root  above  the  artificial  dummy,  as  the 
patient  insisted.  Having  arrived  at  this  conclusion,  I  proceeded  as  tact- 
fully and  kindly  as  I  could  to  explain  my  belief  to  the  patient.  Where- 
upon she  broke  down  and  cried,  displaying  definite  symptoms  of  hysteria. 
I  want  it  distinctly  understood  that  I  did  not  blame  the  patient  for 
her  condition ;  that  I  was  not  out  of  patience  with  her ;  that  I  did  not 
tell  her  there  was  nothing  the  matter  with  her — for  there  was,  though  the 
seat  of  the  trouble  was  not  the  bridge.  And  this  I  tried  to  make  her  un- 
derstand. After  she  had  recovered  somewhat  from  her  crying,  I  said: 
"Xow  I  do  not  want  to  take  that  bridge  off,  for  I  know  there  is  no  root 
beneath  it.  I  do  not  need  to  look  and  see,  as  you  ask  me  to.  But  I  know 
a  way  of  looking  at  the  bridge  so  we  can  both  see  it  if  there  is  any  root 
there,  or  if  either  of  the  crowned  teeth  are  at  all  diseased.  If  I  can  show 
you  beyond  the  shadow  of  all  doubt  that  there  is  no  root  there,  will  you 
believe  that  what  I  have  been  telling  you  is  perhaps  true,  that  the  bridge 
is  all  right,  and  that  you  are  falling  into  faulty  habits  of  thought?"  She 
said  she  would. 

The  radiograph  (  Fig.  298 )  shows  there  is  no  root  above  the  lateral 
dummy,  that  the  canals  of  the  central  and  cuspid  are  properly  filled,  and 
that  the  tissues  at  their  apices  are  not  diseased.  The  radiograph  of  her 
own  case,  together  with  several  others  showing  roots  above  bridges,  ab- 
scesses and  perforations,  were  shown  and  explained  to  the  patient.  I  did 
not  attempt  to  force  her  to  admit  that  I  had  been  right  in  my  diagnosis  of 
her  case,  nor  did  she  do  so  verbally ;  but  she  has  not  returned  for  further 
treatment,  and  she  still  wears  the  bridge. 

61.    Tn  Gases  Ulhcrc  the  Patient  Cannot  Open  the  mouth  Ulide  enough 
Tor  an  Ocular  examination. 

An  impacted  lower  third  molar  sometimes  causes  a  false  ankylosis. 
We  suspect  the  presence  of  the  impacted  tooth,  but  are  unable  to  demon- 
strate it  except  by  the  use  of  the  radiograph  made  on  a  large  plate  (Figs. 
101  and  102  1  or  a  film  on  the  outside  of  the  mouth  (Fig.  97).  With  the 
radiograph  to  confirm  suspicions  and  show  the  exact  location  of  the  of- 
fending tooth,  the  operator  may  proceed  to  anesthetize  the  patient,  force 
the  mouth  open  with  a  mouth  prop  and  extract  the  tooth. 

I *ig.    299   i-   a   case   in    which   the   mouth   could 
fjg.  299.  not  be  opened  because  of  the  inflammation  caused  by 

the  impacted  lower  third   molar  seen  in  the  radio- 
graph. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     263 

62.  Tn  Research  Work  to  Study  Osteology,  the  Development  of  the  teeth,  Action  of 
Bismuth  Paste,  Bone  Production  and  Destruction,  Changes  Occurring  in  the  tern- 
poro-ltlandibular  Articulation  When  Dumping  the  Bite,  Blood  Supply  to  Parts,  Re- 
sorption of  teeth  and  the  Causes  for  Tt.  €tc. 

The  value  of  the  radiograph  to  the  man  who  is  looking  for  the  just- 
how  and  why  of  things  is  clearly  apparent.  It  obviates  the  necessity  of 
conjecture,  and  gives  us  simple,  indisputable  facts.     Many  problems  now 


Fig.    299.       Impacted    lower    third     molar,     causing    a    false    ankylosis.       (Radiograph    by    Graham. 

of   Detroit.) 


confronting  the  dental  scientist  can  be  solved  only  by  the  intelligent  and 
persistent  use  of  the  X-rays. 

It  is  not  my  intention  now  to  tell  of  all  the  different  uses  to  which 
the  radiograph  has  been  and  may  be  put  in  the  broad  field  of  dental 
scientific  research.     I  could  not  if  I  tried.     I  shall  mention  but  a  few. 

Dr.  Joseph  Beck,  by  the  use  of  the  stereoscopic  radiographs,  is  mak- 
ing a  comparative  study  of  the  pneumatic  sinuses  of  man  and  the  lower 
animals. 


264 


DEXTAL  RADIOGRAPHY 


Dr.  Johnson  Symington  and  Dr.  J.  C.  Rankin  have  recently  published 
a  book,  "An  Atlas  of  Skiagrams;'  illustrating,  in  twenty  radiographs,  the 
development  of  the  teeth  and  jaws  from  birth  to  the  age  of  sixteen  years. 

I  have  demonstrated  the  action  of  bismuth  paste  in  one  case.  (Fig. 
223.  )  No  definite  conclusions  should  be  drawn  from  this  single  case.  The 
field  of  research  work  along  this  line  is  still  wide  open  and  inviting  in- 
vestigation. 


Fig.  300.  Fig.  301. 

Fig.    300.      Abscessed    upper    lateral    incisor,    causing    disintegration    of   the    built-in    bone    at   the 

apex  of  the  central  incisor.     (Radiographed  by  Schamberg,  of  New  York  City.) 
Fig.   301.     The   same  as   Fig.  300  after  treatment   and  filling  of  the  canal   of  the   lateral.      Bone 
is   being  rebuilt   into   the   abscess  cavity  at   the   apex   of   the   central.      (Radiographed   by    Scham- 
berg, of  New  York  City.) 


Bone  production  and  destruction  in  alveolar  abscesses  is  a  matter  of 
which  we  know  entirely  too  little.  A  systematic  radiographic  study  of 
the  subject  is  bound  to  result  in  the  disclosure  of  interesting  and  im- 
portant facts. 

A  question,  the  answer  to  which  is  of  extreme 
Tigs.  300  and  301.  importance  is,  "Do  alveolar  abscess  cavities  become 
filled  with  bone  after  the  abscess  is  cured?"  My  ex- 
perience leads  me  to  believe  they  do ;  but  the  new  bone  is  not  so  dense, 
and  it  is  susceptible  to  ready  disintegration  as  a  result  of  contiguous  in- 
flammation. To  elucidate:  Observe  Fig.  300,  a  case  from  the  practice 
of  I  Jr.  R.  Ottolengui.  Note  the  light  areas  at  the  apices  of  both  the  cen- 
tral and  lateral.  A  cursory  observation  of  the  radiograph,  and  a  failure 
to  consider  clinical  history,  would  result  in  the  diagnosis  of  abscess  of 
both  the  central  and  lateral.  Observe,  please,  however,  that  the  canal  of 
the  central  i-,  well  filled,  while  the  canal  of  the  lateral  is  not  filled  at  all. 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY    265 


§  o 


266  DEXTAL   RADIOGRAPHY 

The  central  had  been  filled  three  years  previously  to  the  making  of  the 
radiograph,  and  there  had  been  no  recurrence  of  the  abscess  during  that 
time.  The  lateral  was  treated  and  its  canal  filled,  when  all  symptoms  of 
abscess  disappeared,  proving  it  to  be  entirely  responsible  for  the  trouble. 
Fig.  301  was  made  one  week  after  the  canal  of  the  lateral  was  filled. 
What  I  shall  speak  of  now  I  fear  cannot  be  seen  in  the  accompanying 
half-tone ;  but  it  can  be  observed  easily  in  the  negatives.  At  the  apex  of 
the  central  there  is  a  disposition  of  bone  in  the  old  abscess  cavity.  The 
bone  is  not  as  dense  as  the  surrounding  structure,  and  hence  the  outline 
of  the  old  cavity  can  still  be  seen ;  but  it  is  sufficiently  dense,  so  that  it 
can  be  observed  distinctly,  and  especially  well  when  compared  with  the 
cavity  at  the  apex  of  the  lateral,  which  has  not  been  freed  from  infection 
long  enough  to  permit  of  an  osseous  formation  within  it. 

Just  what  changes  occur  in  the  temporo-mandibular  articulation  when 
"jumping  the  bite"  is  still  an  unsettled  question.  It  is  extremely  difficult 
to  radiograph  this  articulation,  but  it  can  be  done,  and  it  is  not  unreason- 
able to  expect  that  some  day  the  radiograph  will  show  us  just  what  occurs. 
Dr.  H.  A.  Ketcham,  of  Denver,  is,  and  has  been  for  some  time,  working 
in  this  field  of  research. 

Dr.  Cryer.  in  a  recent  article  on  the  study  of  blood  supply  to  the  jaws 
and  teeth,  printed  a  radiograph  of  a  disassociated  mandible  injected  with 
mercury.  How  well  blood  supply  may  be  studied  by  injecting  the  vessels 
with  bismuth  paste,  or  some  other  substance  opaque  to  the  rays,  then 
making  a  radiograph  is  obvious  and  most  encouraging  to  the  student. 

The  radiographs  are  of  a  little  girl  eleven  years 
Tig.  302.  of  age.    They  demonstrate  the  congenital  absence  of 

the  following  teeth:  In  the  upper  jaw  both  lateral 
incisors,  one  cuspid  and  one  bicuspid;  in  the  lower  jaw  three  bicuspids, 
making  in  all  seven  permanent  teeth  congenitally  absent  from  the  jaws. 
Despite  the  absence  of  the  permanent  teeth  resorption  of  the  roots  of  the 
temporary  teeth  occurs,  showing  that  the  resorption  is  not  dependent  on 
the  eruption  of  the  permanent  teeth.  I  do  not  make  the  statement  that 
the  temporary  tooth  roots  resorb  independently  of  the  succedaneous  teeth. 
because  of  what  I  see  in  the  radiograph  in  Fig.  302.  Fig.  302  but 
illustrates  what  has  been  observed  in  many  other  radiographs. 

Dr.  II.  A.  Ketcham,  with  the  aid  of  radiographs,  has  endeavored  to 
disprove  thai  certain  orthodontic  procedures  caused  impaction  of  the 
third  molar-. 

The  discussion  of  the  orthodontic  procedure  of 

TiflS.  303  and  304.       "opening  the  maxillary  suture"  is  one  In   which  the 

radiograph  is  yet  playing  an  important  role.     That 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     267 

this  suture  can  be  opened  is  claimed  by  Dr.  Varney  C.  Barnes.  Figs.  303 
and  304  are  from  the  practice  of  Dr.  Barnes.  How  wide  it  may  be  opened, 
the  permanency  of  the  separation  of  the  bones,  and  the  benefits  to  be 
derived  from  the  operation  I  shall  not  discuss,  but  radiography  will  al- 
ways  be  a  valuable  aid  in  determining  the  condition,  both  before  and  after 
treatment. 

In  the  discussion  of  a  paper,  read  at  a  dental  society  meeting.  Dr. 


Fig.  303.  Fig.  304. 

Fig.   303.      Before  attempting  to  open   the   maxillary   suture.      (Radiographed   by    Lodge,   of 

Cleveland.) 

Fig.    304.      Same    case    as    Fig.    303    fourteen    days    later,    after    attempt    to    open    the    maxillary 

suture.      (Radiographed   by    Lodge,    of    Cleveland.) 


Don  Graham  recently  said:  "If  the  radiograph  has  done  nothing  else  it 
has  proven  beyond  all  doubt  that  the  best  canal  rilling  in  use  to-day  is 
gutta-percha." 

Likewise  radiographs  have  shown  us  that,  when  filling  canals  with 
large  apical  foramina,  we  would  better  force  a  little  gutta-percha  through 
the  apex  rather  than  to  fall  short  of  reaching  the  end  of  the  root.  Of 
the  two  mistakes,  filling  a  little  beyond  or  not  quite  to  the  apex,  the  former 
seldom  causes  trouble,  while  the  latter  almost  always  results  in  the  re- 
currence of  the  abscess. 

The  radiograph  shows  an  upper  cuspid  with  a 

Tig.  305.  perforation  to  the  mesial  through  the  side  of  the  root 

into  the  peridental  membrane.     The  radiograph  was 

made   several   weeks  after  patching  the  perforation   with  gutta-percha. 

There  is   scarcely  any   inflammation  at   all  at  the  point  of  perforation. 

showing  how  well  the  tissues  tolerate  gutta-percha. 

Under  this  heading  of  research  work  allow  me  to  mention  the  recent 


268  DEXTAL   RADIOGRAPHY 

disturbing  paper  by  Dr.  William  Hunter,  of  London.  Let  me  say  that 
Dr.  Hunter's  charge  that  we,  as  a  profession,  practice  septic  dentistry  is 
well  founded.  One  needs  to  do  but  little  radiographic  work  to  be  fully 
convinced  that  the  conservative  dentistry  of  which  we  have  been  so  proud 
is  often  a  dreadful  mistake.  It  consists  all  too  often  of  simply  treating 
the  case  until  it  becomes  a  chronic  abscess,  then,  with  the  abatement  of 


Fig.    305.      The  arrow   points   to   a   perforation,   through   the   side   of   the   cuspid   root,    which    has 

been  patched  with   gutta-percha. 


the  acute  symptoms,  calling  the  case  cured.  As  a  radiographer,  a  man  in 
a  position  to  make  extensive  observations,  I  declare  that  the  root  canal 
work  of  the  majority  in  our  profession  is  a  disgrace  and  a  menace  to 
health.  Bad  root  canal  work  is  not  usually  the  result  of  inability  to  do 
the  work  properly,  so  let  us  have  hope.  It  is  nearly  always  due  to  the 
fact  that  the  operator  thinks  he  cannot  get  paid  for  the  work.  And  it  is 
indeed  hard  to  convince  a  public,  which  has  received  its  dental  education 
from  advertising  quacks,  of  the  necessity  of  receiving  and  paying  for  the 
proper  treatment  of  its  teeth. 

I  would  not  be  understood  as  saying  that  I  agree  fully  with  Dr. 
Hunter.  1  do  not.  But  the  doctor  is  on  the  right  track.  He  knows  there 
is  such  a  thing  as  bad  dentistry,  septic  dentistry,  being  practiced,  as  do  all 
observing  men.  especially   radiographers. 

63.    R$  a  Record  of  Ulork  Done. 

Any  sort  of  a  record  of  work  done  is  always  valuable.  Radiographic 
records  of  canal  fillings,  extractions  and  the  like  are  often  of  the  utmost 
value  to  the  operator.  Such  records  would  be  of  the  most  gratifying 
service  in  the  unpleasant  event  of  being  tried  for  malpractice.     A  patient, 


THE  USES  OF  THE  RADIOGRAPH  IN  DENTISTRY     269 

let  us  say,  finds  it  necessary  to  go  to  the  hospital  for  a  week  after  the 
extraction  of  a  badly  impacted  third  molar.  The  next  thing  the  operator 
knows  is  that  suit  has  been  brought  against  him.  He  learns  that  he  "broke 
the  jaw-bone,"  and  that  the  patient  is  to  remain  a  "helpless  invalid  for 
the  balance  of  her  life,"  because  of  "his  lack  of  skill,  his  ignorance  and 
brutality."  Radiographs  of  the  case  showing  just  what  had  been  done 
for  the  patient  might  prevent  the  suit  or  win  the  case  for  the  operator. 

In  cases  where  the  patient  is  seized  with  a  decided  disinclination  to 
pay  a  dental  bill  the  radiograph  may  sometimes  be  used  to  advantage. 
These  patients  usually  suffer  from  the  loss  of  memory,  and  tell  the  judge 
that  the  plaintiff  is  quite  mistaken  in  imagining  that  he  filled  their  root 
canals.  Radiographs  would  go  far  toward  convincing  the  judge  of  the 
validity  of  the  claim. 

64.    Tn  Cases  of  Ridden  Dental  Caries. 

The  "diagnosis  of  hidden  dental  caries  by  means  of  radiographs"  was 
suggested  and  recommended  by  Drs.  H.  W.  C.  and  C.  F.  Bodecker  in  a 
short  unillustrated  paper  printed  in  the  Dental  Review,  April,  1912.  I 
quote  a  paragraph  from  the  article  referred  to.  "The  diagnosis  of  caries 
in  its  first  stages  on  the  proximal  surfaces  of  molars  and  bicuspids  is 
often  difficult,  and  frequently  patients  complain  of  sensations  at  points 
where  we  cannot  discover  caries  either  with  floss  silk  or  explorer.  Sep- 
aration then  has  to  be  resorted  to,  in  order  to  definitely  locate  the  trouble. 
Sometimes  the  patient  is  not  able  to  point  out  any  single  tooth  in  which 
he  notices  the  sensation ;  he  simply  tells  us  that  it  is  'somewhere  on  that 
side,'  and  passes  the  finger  over  two  or  three  teeth.  Another  factor 
which  makes  diagnosis  difficult  is  reflex  pain.  Frequently  the  irritation 
is  in  an  upper  tooth,  and  the  patient  experiences  the  pain  in  a  lower  one. 
and  vice  versa.  Therefore,  to  obviate  the  useless  separation  of  teeth  in 
locating  small  carious  spots,  we  have  used  the  Roentgen  apparatus.  It 
would,  nevertheless,  be  a  useless  expenditure  of  time  and  work  to  radio- 
graph two  or  three  teeth  in  the  upper  arch,  and  if  no  defect  had  been 
found  to  repeat  the  same  in  the  lower.  We  have,  therefore,  constructed 
a  film  holder  by  the  aid  of  which  the  crowns  of  the  bicuspids  and  molars 
of  one  side  can  be  photographed  at  one  time." 

Personally,  I  have  never  put  the  radiograph  to  the  use  suggested  by 
the  Doctors  Bodecker,  but  it  is  my  intention  to  do  so. 

And  so — we  have  passed  over  the  uses  of  the  radiograph  in  the  prac- 
tice of  modern  dentistry,  and  it  has  been  a  long  trip.  Permit  me  to  repeat 
what  I  said  at  the  beginning  of  the  chapter,  for  you  are  now  better  able 
to  understand  and  believe  me.  Of  the  uses  for  the  radiograph  enu- 
merated, some  are  of  cases  that  the  general  practitioner  of  dentistry  mav 


270  DENTAL  RADIOGRAPHY 

not  be  called  upon  to  diagnose  or  treat  oftener  than  once  or  twice  in  a 
lifetime,  perhaps  not  at  all;  but  by  far  the  greater  number  are  of  cases 
the  like  of  which  we  meet  almost  daily  in  the  practice  of  dentistry. 

There  is  a  popular  belief  among  dentists  at  large  that  the  use  of  the 
radiograph  is  indicated  only  in  the  baffling,  the  exceptional,  the  icono- 
clastic cases  in  our  practice.  This  is  not  true.  It  is  a  fact  that  the  radio- 
graph, in  a  spectacular  manner,  has  been  responsible  for  the  diagnosis 
and  cure  of  many  baffling  cases.  But  I  am  tempted  to  say  that  this  is 
unfortunate.  For  the  radiograph  does  not  always  solve  the  mysteries  of 
the  refractory  cases,  though  practitioners  of  dentistry  and  medicine  pay 
it  the  embarrassing  and  unfair  compliment  of  expecting  it  to  do  so.  The 
radiograph's  most  potent  value  in  dentistry  is  in  the  ordinary,  the  every- 
day cases  which  come  to  our  offices — in  cases  of  impacted  teeth  as  an  aid 
in  extraction ;  in  cases  where  the  apical  foramen  is  very  large  as  an  aid 
in  filling  the  canals  properly ;  in  cases  where  apical  sensitiveness  may  be 
due  to  a  large  apical  foramen  or  an  unremoved,  undevitalized  remnant  of 
pulpal  tissue ;  in  cases  of  retained  temporary  teeth  to  learn  if  there  be 
succedaneous  teeth  present  in  the  jaw;  in  cases  of  badly  decayed  teeth  of 
the  secondary  set  in  the  mouths  of  children  to  learn  if  the  roots  of  the 
diseased  teeth  are  fully  formed ;  in  cases  of  abscess  to  determine  which 
tooth  is  affected ;  in  cases  of  traumatism,  and  so  on.  It  is  in  these  cases, 
met  constantly,  that  we  may  use  the  radiograph  and  derive  the  greatest 
assistance  and  benefit.  In  baffling  cases  we  will  often  be  disappointed  in 
our  use  of  the  radiograph,  but  in  the  ordinary  cases,  such  as  I  have  just 
enumerated,  never,  for  we  know  just  what  to  expect,  and  we  do  not  ex- 
pect too  much. 

It  should  ever  be  borne  in  mind  when  using  the  radiograph  for  diag- 
nostic purposes  that  it  is  only  an  aid;  in  many  cases  the  greatest  aid  we 
have,  but,  nevertheless,  only  an  aid  in  diagnosis.  No  other  methods  or 
means  of  diagnosis  should  be  forgotten  or  slighted. 

When  the  use  of  the  radiograph  fails  to  reveal  the  cause  of  the 
trouble  it  is  not  fair  to  look  upon  its  use  as  of  no  assistance  or  value.  For 
example,  a  patient  is  suffering  from  false  ankylosis.  Judging  from  the 
symptoms  we  suspect  an  impacted  lower  third  molar  to  be  the  active 
cause.  We  make  a  radiograph  and  fail  to  find  an  offending  third  molar 
or  anything  else  that  might  be  responsible  for  the  ankylosis.  It  is  natural 
that  we  should  be  disappointed,  but  we  must  not  feel  that  the  radiograph 
has  been  of  no  service  at  all,  for  we  now  know  that  an  impacted  third 
molar  is  n<>t  the  cause  of  the  trouble,  and  we  have  taken  an  important 
step  in  diagnosis  by  elimination. 

In  printing  the  great  number  of  radiographs,  which  have  appeared  in 
this  chapter,  it  is  inevitable  that  some  should  not  be  good.     It  must  be 


THE  USES  OE  THE  RADIOGRAPH  IN  DENTISTRY     271 

remembered,  too,  that  only  an  idea  of  what  can  be  seen  in  negatives  can 
be  learned  from  half-tones.  It  has  been  most  discouraging  to  the  writer 
to  observe,  at  times,  the  great  loss  of  detail  in  the  printed  half-tones,  as 
compared  to  the  original  negative.  I  wish  to  state  most  emphatically, 
however,  that  with  the  rarest  exception  the  loss  of  detail  was  not  the 
result  of  incompetency  on  the  part  of  the  makers  of  the  half-tone  plates. 
This  most  complete  collection  of  dental  radiographs  ever  made  has  been 


Fig.  306.  Fig.  307. 

Fig.    306.     The   arrows   point   to   the   ends    of   what   might    have    been    mistaken    for   a   line   of 

demarcation. 
F*ig.  307.     The  same  case  as  Fig.  306,  proving  the  line  seen  in  Fig.  306  to  be  a  fault  in  the  film. 


transferred  from  the  photographic  print  to 'the  half-tone  in  a  masterful 
way,  and  its  failure  to  be  perfect  represents  only  the  shortcoming  of  the 
process  itself. 

Misinterpretation  of  radiographs  is  one  of  the  easiest  things  in  the 
world  and,  for  this  reason,  I  can  already  hear,  in  imagination,  the  cries 
of  condemnation  of  the  disappointed  ones  who  will,  within  the  next  few 
years,  take  up  dental  radiographic  work.  I  believe  that  no  one  who  has 
ever  done  radiographic  work  has  experienced  disappointment  more  often, 
or  more  keenly,  than  I  have.  But  every  radiograph  ever  made  is  the 
product  of  simple  physical  and  chemical  laws,  and  when  misread  the 
fault  usually  lies  in  the  reader. 

Very  often  it  is  expedient  to  make  several  radiographs  of  the  same 
part,  changing  the  pose  slightly  to  verify  or  disprove  the  findings  in  the 
first  picture  of  the  part. 

Fig.    306    is    a    case    from    which    a    first    molar 

Ti9$.  306  and  307.       tooth  and  sequestrum  had  previously  been  removed, 

because  of  arsenic  poisoning.     The  radiograph  was 

made  to  learn  if  all  the  sequestrum  had  been  removed.     It  shows  to  the 

inexperienced  reader  what  would  appear  to  be  a  line  of  demarcation  and 


272  DENTAL   RADIOGRAPHY 

a  large  sequestrum  involving  the  lower  border  of  the  mandible.  The  line, 
however,  has  not  the  typical  appearance  of  a  line  of  demarcation  and  the 
sequestrum  (  ?)  does  not  look  like  diseased  bone.  Two  more  radiographs 
(one  of  which  is  shown  in  Fig.  307)  were  made  and  show  no  line,  prov- 
ing the  line  on  the  first  picture  to  be  a  fault  in  the  film. 

When  I  started  this  chapter  I  expected  to  close  it  by  quoting  words 
of  praise  for  the  radiograph,  spoken  and  written  by  the  leading  men  in 
the  dental  profession.  I  shall  not  take  the  space  to  do  this,  but  shall  tell 
you  simply  that  I  could  if  I  wished.  I  shall  quote  but  one  man  who,  in 
an  impromptu  discussion,  voiced  the  sentiments  of  all.  Though  he  is  a 
specialist  in  oral  surgery,  he  speaks  as  well  for  the  orthodontist,  the  ex- 
tracting specialist  and  the  general  practitioner.  Dr.  T.  W.  Brophy  said 
"Now  that  we  have  the  X-ray  picture  to  help  us,  I  do  not  see  how  we 
could  possibly  get  along  without  it." 

The  greatest  argument  in  favor  of  the  use  and  value  of  the  radio- 
graph, however,  does  not  lie  in  the  enthusiastic  and  inspiring  remarks 
concerning  its  value,  but  in  the  irrefutable  facts  set  forth  and  illustrated 
in  this  chapter. 

Seldom,  indeed,  is  the  use  of  the  radiograph  in  dentistry  a  matter  of 
life  or  death  to  the  patient,  though  it  may  sometimes  be,  but  often,  often 
indeed,  does  health  and  happiness  depend  on  its  use. 


CHAPTER  VIII. 

the  Dangers  of  the  XRay. 

A  work  of  this  kind  would  be  worse  than  incomplete,  it  would  be  a 
positive  menace  to  the  welfare  of  the  public  and  the  profession,  without 
a  chapter  devoted  to  vigorous  warning  of  the  evil  results  that  may  occur 
from  exposure  to  the  X-rays. 

The  following  unfortunate  results  have  been  attributed  to  the  action 
of  the  X-rays:  dermatitis  {i.e.,  X-ray  burn),  cancer,  leukemia,  sterility, 
abortion,  insanity,  lassitude  and  alopecia. 

YVe  will  now  consider  each  of  these  foregoing  dangers,  taking  them 
up  in  the  order  named. 

X-ray  burns  are  of  two  kinds,  acute  dermatitis  and  chronic  derma- 
titis. 

Acute    dermatitis*    manifests    itself    anywhere 
Acute  Dermatitis.       from  twenty-four  hours  to  (in  rare  cases)  as  long  as 
two  or  three  months  after  exposure  to  the  rays.    The 
time,  however,  is  usually  from  three  to  fifteen  days. 

Itching  and  redness  are  the  first  symptoms  to  appear.  The  itching 
becomes  intense,  swelling  occurs,  the  skin  grows  harsh  and  dry,  and  has  a 
smooth,  glossy  appearance. 

In  mild  cases  the  inflammation  subsides  gradually  after  a  few  days 
and,  depending  on  the  severity  of  the  burn,  may  or  may  not  be  followed 
by  desquamation  and  loss  of  hair. 

This  Elberhart  calls  an  acute  dermatitis  of  the  first  degree. 

In  the  more  severe  form  of  acute  dermatitis,  termed  by  Elberhart  of 
the  second  degree,  there  will  be  the  formation  of  a  blister  with  the  usual 
serous  exudate  and  marked  neuralgic  pains. 


^Elberhart  "Practical  X-Ray  Therapy." 

?73 


274  DEXTAL   RADIOGRAPHY 

In  the  very  severe  cases  of  acute  dermatitis,  where  the  deeper  layers 
of  the  skin  and  underlying  tissues  are  affected,  a  slough  forms  and  the 
destructive  condition  shows  a  marked  tendency  to  spread  and  become  ma- 
lignant.   Severe  pain  in  these  latter  cases  is  a  wellnigh  constant  symptom. 

After  exposing  himself  to  the  X-rays  a  great 

Chronic  Dermatitis,      number  of  times,  and  having  had  a  number  of  mild 

attacks  of  acute  dermatitis — or  perhaps  without  ever 


w 


Fig.    308.     Chronic   X-ray   Dermatitis. 


having  had  acute  dermatitis — the  X-ray  operator  notices  certain  tissue 
changes  occurring,  usually  on  the  back  of  the  hands,  sometimes  on  the 
face  and  chest.  The  hands,  face  and  chest  are  most  likely  to  become  af- 
fected, because  these  parts  are  the  most  exposed  to  the  rays.  There  is  a 
pigmentation  of  the  skin  very  similar  to  tanning,  such  as  sun  and  wind 
will  produce.  Freckles  occur  in  some  cases.  The  skin  becomes  harsh,  dry 
and  wrinkled — the  same  changes  that  occur  with  age.  Hair  drops  out. 
The  fingernails  become  brittle  and  thin  and  ridged  longitudinally.  Small, 
hard,  scabby  growths  (keratoses)  occur  here  and  there.  These  growths 
break  down  into  ulcers,  which  often  become  cancerous.    (Fig.  308.) 

There  has  been  a  great  deal  of  discussion  as  to 
Cancer.  whether  X-rays  can,  or  cannot,  produce  cancer,  but 

in  the  face  of  such  reports  as  Dr.  C.  A.  Porter's*  I 
do  not  see  how  anyone  can  dispute  it.  According  to  the  highest  author- 
ities, X-rays  can,  and  have,  produced  carcinoma.     In   1907  Dr.  Porter  re- 

"The    Surgical    Treatment    of    X-Ray    Carcinoma   and    Other    Severe    X-Ray 
Lesions,  Based  Upon  an  Analysis  of  Forty-seven   Cases." 


THE  DANGERS   OF   THE  X-RAY  275 

ported  eleven  cases  of  "unquestionable  X-ray  cancers,"  six  of  which 
proved  fatal. 

Cancer  usually  follows  a  chronic  dermatitis,  occurring  at  the  site  of 
a  former  ulcer,  though  it  may  result  from  a  very  severe  acute  dermatitis. 
When  cancer  follows  chronic  dermatitis  the  victim  is  almost  invariably 
an  X-ray  operator ;  when  it  follows  acute  dermatitis  the  victim  is  usually 
a  patient  who  has  been  exposed  to  the  rays  for  therapeutic  purposes. 

Even  before  the  formation  of  cancer,  when  chronic  ulcers  appear, 
operation  after  operation  becomes  necessary.    These  operations  consist  of 


Fig.    309.      X-ray    Cancer. 

a  curettement  of  the  ulcer  and  skin  grafting.  With  the  formation  of  can- 
cer commences  amputation.  First  one  finger,  then  another,  then  two  more, 
then  a  hand,  both  hands,  an  arm.  A  welcome  death,  due  usually  to  the 
formation  of  metastatic  cancers  throughout  the  vital  organs  of  the  body, 
is  the  next  step  of  the  progressive  case. 

I  print  reports  here  by  Dr.  Porter  of  two  more  or  less  typical  cases 
of  fatality  due  to  X-ray  lesions : 

"Case  XXXI — Man,  32  years  old,  who,  after  three  years  of  X-ray 
work,  suffered  from  severe  lesions  on  both  arms,  breast,  neck  and  face. 
In  1901  there  began  a  slowly  growing  ulceration  of  the  back  of  the  right 
hand,  which,  by  the  middle  of  1902,  had  become  a  gangrenous  epithelioma ; 
glands  enlarged  at  the  elbow  and  in  the  axilla.  Amputation  at  the  shoul- 
der; axillary  glands  removed,  and  found  full  of  squamous-celled  car- 
cinoma. Sound  healing.  In  December,  1904,  a  typical  cancer  of  the  lower 
lip  and  another  of  the  angle  of  the  mouth  were  excised,  as  was  a  suspicious 


276  DEXTAL  RADIOGRAPHY 

lesion  on  the  back  of  the  left  hand.  In  March,  1905,  a  growth  of  the  cheek 
was  removed,  which  was  pronounced  by  Unna  to  be  a  sarcoma.  In  Sep- 
tember, 1905,  excision  of  the  right  lower  jaw  for  carcinoma.  Recurrence, 
involving  the  tongue  and  the  adjacent  cheek,  was  present  in  February, 
1906.     Death  soon  followed." 

"Case  XLVII.     Summary:    In   1897  began  work  with  the  X-rays, 
testing  the  tubes  for  several  hours  a  day.     First  noticed  erythema  and 


Fig.    310.      Hands    of    X-ray    operator    after    thirty    operations. 

warty  growths  in  1900.  In  1905,  keratoses  and  warts  had  formed  on  both 
hands,  chest  and  face.  First  carcinoma  developed  and  required  amputa- 
tion of  two  fingers  of  the  left  hand  in  April,  1907 ;  similar  growth  curetted 
on  right  hand.  By  March,  1908,  rapid  extension  of  the  disease  necessi- 
tating amputation  of  left  forearm ;  curettage  of  epithelioma  on  right  hand. 
August,  1908,  involvement  of  epitrochlear  and  axillary  glands.  August 
11,  1908,  amputation  of  fingers  of  right  hand.  September  25,  1908,  ampu- 
tation at  shoulder.  Death  on  November  7,  1908;  general  carcinosis."   ( Fig. 

309- ) 

The  report  of  another  case  by  Porter  commences : 

"1  have  operated  upon  this  patient  under  ether  thirty-two  times,  the 
operations  varying  in  duration  from  one  hour  and  a  half  to  three  hours. 
At  present  there  remains  of  his  left  hand  two  joints  of  the  little  finger, 
the  forefinger  and  thumb ;  of  the  right  hand,  the  thumb,  the  middle  finger, 
barring  part  of  the  terminal  phalanx,  and  one  and  a  half  phalanges  of  the 
little  finger.  More  than  half  of  the  skin  of  the  backs  of  both  hands  con- 
sists of  Thiersch  grafts."     (Fig.  310.) 


Figs.  308,  309,  310,  copied  by  permission   from  The  Journal  of  Medical  Re- 
search. 


THE  DANGERS   OF   THE   X-RAY  277 

Regarding  the  pain  suffered  by  these  patients,  with  severe  chronic 
dermatitis  and  cancer,  Porter  says :  "The  amount  of  pain  suffered  is 
variable  though  usually  extreme.  From  my  experience  and  personal  com- 
munications with  patients,  I  believe  that  the  agony  of  inflamed  X-ray 
lesions  is  almost  unequaled  by  any  other  disease." 

Leukemia  is  a  blood  disease  characterized  by  an 
Eeukcmia.  increase  in  the  number  of  white  blood  cells.     The 

cardinal  symptoms  of  the  disease  are  insidious  ema- 
ciation and  lassitude.  It  is  generally  fatal.  Practically  nothing  is  known 
concerning  its  etiology.  It  is  suspected  that  continued  exposure  to  the 
X-rays  may  produce  leukemia  but,  as  yet,  this  supposition  has  not  been 
scientifically  substantiated. 

X-ray  operators  of  the  male  sex,  who  subject 
Sterility.  themselves  to  repeated  mild  exposures  to  the  rays, 

are  often  sterile.  This  sterility  is  due  either  to  the 
death  of  the  spermatozoa,  or  to  their  complete  disappearance  from  the 
semen.  This  condition  has  no  effect  one  way  or  the  other  on  the  carnal 
instincts  of  the  individual,  and  if  the  victim  will  discontinue  exposing  the 
parts  to  the  X-rays,  virility  will  be  regained.  Likewise  repeated  exposures 
of  the  ovaries  to  the  X-rays  will  produce  sterility  in  the  female  by  causing 
a  disappearance  of  the  Graafian  follicles ;  the  menses  do  not  cease,  and 
sexual  animation  remains  unaltered.  As  with  the  male,  the  power  of  re- 
production is  regained  promptly  when  the. parts  are  no  longer  subjected 
to  X-radiation. 

Quoting     from     Elberhart     (Practical     X-Ray 
Abortion.  Therapy)  :     "Fraenkel  claims  that  the  Roentgen  ray 

retards  the  growth  of  the  ovum  and  tends  to  produce 
abortion  when  the  thyroid  gland  and  ovaries  are  exposed  to  it." 

Fraenkel  has  in  mind  the  use  of  the  X-rays  as  a  therapeutic  agent, 
and  mentions  a  case  of  induced  abortion  after  twenty-five  exposures  of 
five  or  ten  minutes  each  every  other  day. 

For  the  slight  radiation  required  for  dental  radiographic  work  preg- 
nancy cannot  possibly  be  considered  a  contra-indication. 

There  is  a  somewhat  popular  superstition  that 
Tnsanity.  X-rays  will  produce  insanity  in  those  who  constantly 

expose  themselves  to  their  action.  This  belief  arose, 
I  think,  from  the  fact  that  a  prominent  X-ray  operator  lost  his  mind  a  few 
years  ago.  So  far  as  I  know  he  is  the  only  X-ray  operator,  of  the  thou- 
sands engaged  in  the  work,  who  has  met  with  such  a  misfortune,  and  it  is 
as  ridiculous  to  blame  the  X-rays  for  it  as  it  would  be  to  claim  that  his 
insanity  was  caused  by  the  suspenders  he  wore. 


2;8  DEXTAL  RADIOGRAPHY 

There  is  a  belief  among  operators  themselves  that  X-ray  operators 
develop  a  "nervous,  restless,  intense  personality."  Whether  the  develop- 
ment of  such  a  personality  is  clue  to  the  electric  condition  of  the  atmos- 
phere of  the  operating  room,  to  the  action  of  the  X-rays,  or  to  the  enthu- 
siastic interest  developed  by  research  work  is  a  matter  of  conjecture.  Per- 
sonally I  do  not  believe  any  of  these  things  are  responsible  for  the  restless, 
nervous  personality  of  so  many  operators.  These  men  were  of  a  restless 
disposition  before  they  took  up  X-ray  work.  In  fact,  their  adoption  of 
the  work  was  but  a  sign  of  their  restlessness  and  desire  to  be  progressive. 

X-ray  operators  often  complain  of  a  feeling  of 
Lassitude,  utter  exhaustion.    When  it  is  proven  that  X-rays  can 

produce  leukemia,  I  shall  believe  that  this  feeling  of 
extreme  lassitude  is  caused  by  exposure  to  the  X-rays.  Until  then  I  shall 
hold  to  the  belief  that  this  exhaustion,  which  unquestionably  does  occur, 
is  due  to  the  work,  physical  and  mental,  the  bad  air  of  the  dark  room,  and 
the  depressing  disappointments  experienced  by  all  conscientious  radi- 
ographers. 

Loss  of  hair  may  occur  from  a  severe  X-ray 
Alopecia.  burn,  but  I  can  find    no    reliable  authority  who  at- 

tempts to  prove  that  the  X-rays  will  produce  baldness 
of  the  head  without  dermatitis. 

Knowing  now  the  dangers  of  the  X-rays,  how 

Protection.  shall  we  protect  ourselves  and  our  patients  against 

them  ?  We  shall  protect  ourselves  by  never  expos- 
ing any  part  of  our  bodies  to  the  direct  or  primary  X-rays,  and  our  pa- 
tients by  exposing  them  as  short  a  time  as  possible. 

How  can  we  do  radiographic  work  without  exposing  ourselves  to 
the  X-rays? 

Sheet  lead  one-eighth  inch  thick  is  opaque  to  very  penetrating  X-rays. 
Lead  glass — a  transparent  glass  containing  a  great  deal  of  lead  silicate — 
though  it  would  need  to  be  "about  two  inches  thick  to  totally  obstruct  very 
penetrating  X-rays,"  nevertheless  offers  considerable,  and  perhaps  suf- 
ficient, protection  in  the  thickness  of  one-quarter  inch. 

The  writer  was  informed  that  linoleum  is  opaque  to  the  X-rays.  To 
test  the  verity  of  this  information  Figs.  311,  312  and  313  were  made.  A 
study  of  the  illustrations  will  show  that,  compared  to  lead  or  lead  glass, 
linoleum  offers  very  little  resistance  to  the  rays;  compared  to  wood,  the 
resistance  is  much  greater.  White  linoleum  offers  more  resistance  than 
red,  green  or  blue. 


THE   DANGERS   OF   THE    X-K.l) 


279 


Fig.    311.     A.    B.    C,   and    D   are    pieces    of   linoleum.      E,    a    piece    of   sheet    lead    1-16    inch    thick. 


Appliances  for 
Protection. 


The  appliances  which  may  be  used  for  protec- 
tion against  the  X-rays  are :    Protection  lead  screens 
(Figs.  314  and  315),  protection  lead  cabinets  (Figs. 
316  and  317),  protection  shields  for  the  tube  (Figs. 
60,  61,  63  and  64,  Chapter  HI,  and  Fig.  318),  protection  or  safety  X-ray 
tubes   (Fig.  319),  X-ray  proof  gloves  (Fig.  320),  lead  glass  spectacles 
(Fig.  321),  and  protective  aprons. 


DENTAL  RADIOGRAPHY 


Fig.   818.     A.    B,  C,  and    l».  Bame  as  in   Fig.   811.      I-".,  a  piece  of  lead   glass    1-1    inch   thick. 


From  the  standpoint  of  protection  for  the  oper- 

thc  Ccad  Screen        ator  n< -thing  is  so  efficient  as  the  lead  screen  or  cabi- 

and  Cabinet,  nel  (Figs.  314,  315,  316  and  317).     The  use  of  either 

makes  it  possible  for  the  operator  to  protect  himself 

completely  from  all  direct  X-rays. 

The  lead  used  in  protective  screens  and  cabinets  is  usually  one-six- 


THE  DANGERS   OF   THE    X-RAY 


281 


Fig.   313.     A,    B,   C,   and    D,   same   as   in   Fig.    311.     E,  the  dotted   lines   outline   the  position   of  a 
piece   of   pine   wood    1-2    inch    thick. 


teenth  inch  thick.  Lead  of  this  thickness  does  not  totally  obstruct  very 
penetrating  X-rays  when  the  tube  is  brought  close  up  to  it,  but  at  the 
usual  distance  of  several  feet  between  tube  and  screen  it  is  doubtful  if 
any  X-rays  penetrate  the  latter. 

The  lead  glass  used  in  the  windows  in  protection  screens  and  cabinets 
is  usually  one-fourth  inch  thick.     With  the  tube  placed  in  close  proximity 


282 


DENTAL  RADIOGRAPHY 


± ■>'-- '    V 

Fig.  814. 

Fig.    814.     Protective   lead   screen. 
Fig.    816.     Protective    lead    screen,   sectional    view. 


Fig.  81( 


THE   DAXGERS   OE    THE    X-RAY 


283 


Fig.  316.  Fig.    811 

Fig.   316.      Protective   lead   cabinet;    front   view. 
Fig.    317.     Protective   lead   cabinet;    rear    view. 


to  the  screen,  lead  glass  of  this  thickness  is  highly  translucent  to  the 
X-rays,  but  with  the  tube  a  distance  of  several  feet  the  rays  penetrate  the 
glass  but  feebly. 

Instead  of  the  lead  glass  window  a  screen  may  be  covered  entirely 
with  lead  and  mirrors  so  arranged  that  the  operator  may  observe  his  tube 
and  patient  from  his  position  back  of  the  screen. 

Let  it  be  clearly  understood  that  the  man  standing  behind  a  lead 


284 


DEXTAL   RADIOGRAPHY 


Fig.   81  8,     Proti  i  live   tube  Bhield   and   Btand. 

screen  i-  not  completely  protected  from  all  X-rays.  If  the  tube  is  rather 
close  to  the  screen  some  of  the  X-rays  may  penetrate  it— becoming  ex- 
tremely feeble,  however,  by  the  time  they  make  the  penetration— and  he 
is,  of  course,  exposed  to  the  secondary,  tertiary  and  other  sets  of  feeble 
rays  which  fill  the  room  like  light.  But  he  is  completely  protected  from 
the  powerful  dangerous  rays. 


THE   DANGERS   OF   THE   X-RAY  285 

The   protective   lead   screen,   or   cabinet,   or   their   equivalent,    is   a 
necessity  in  the  practice  of  modern  radiography. 

Protection  shields  are  of  three  varieties :  those 
Protection  made  of  lead  glass  (Figs.  60,  61  and  63,  Chapter  III), 

Shields.  those  depending  on  a  sheet  of  metallic  lead  for  their 

action  (Fig.  64,  Chapter  III),  and  those  made  of 
rubber  impregnated  with  lead  or  a  salt  of  lead  (in  appearance  similar  to 
Fig.  64).  The  X-ray  tube  fits  into  the  protection  shield,  which  latter  pro- 
tects the  patient  to  a  great  extent  against  the  action  of  all  X-rays  except 


msa  * 


Fig.    319.     Protection    or    safety.    X-ray    tube. 

those  which  pass  through  the  window  of  the  shield  and  are  being  used 
to  make  the  radiograph.  As  a  matter  of  fact,  the  patient  does  not  need 
this  protection  in  the  practice  of  dental  radiography,  but  it  is  not  inex- 
pedient to  use  even  protective  measures  that  are  thought  to  be  unneces- 
sary. The  operator  is  also  protected  in  a  degree  by  the  protective  shield. 
A  protection  shield  calculated  to  take  the  place  of  a  lead  screen  or 
cabinet  is  illustrated  in  Fig.  318.  The  protective  material  used  is,  I  judge 
from  its  appearance,  rubber  impregnated  with  lead  or  a  salt  of  lead.  The 
manufacturers  claim  to  use  a  German  preparation,  the  formula  of  which 
is  not  divulged.  This  material  is  more  opaque  to  the  X-ray  than  lead 
glass,  less  opaque  than  metallic  sheet  lead. 

Protection  or  safety  X-ray  tubes  are  manufac- 

Protection  tured,  some  of  lead  glass  save  for  a  window  of  ordi- 

X-Ray  Cubes.  nary  glass  transparent  to  the  X-rays,  and  some  with 

an  internal  protective  arrangement  which  allows  the 

X-rays  to  be  given  out  from  the  tube  from  a  limited  place  or  spot  only 

(Fig-  3i9)- 


286  DENTAL   RADIOGRAPHY 

The  hands  of  the  operator  may  be  protected  with 

Gloves.  X-ray  proof  gloves.    These  gloves  are  usually  made 

Tifl.  320.  of  rubber  impregnated  with  lead  or  some  salt  of  lead. 

Protective  gloves  may  be  made  by  painting  ordinary 

leather  gloves  with  several  coats  of  white  lead.     X-ray  proof  or  "opaque" 

gloves,  as  they  are  called,  are  not  really  opaque  to  X-rays ;  they  are,  in 

fact,  quite  translucent  to  powerfully  penetrating  rays. 

Gloves  should  be  used  when  the  operator  finds  it  necessary  to  hold 
the  film  in  the  patient's  mouth  himself.     Seldom,  very  seldom  indeed,  is 


320.  Fig.  321. 

Fig.    320.     X-ray    proof,    opaque,    or    protection    gloves. 
Fig.    321.      Lead    glass    spectacles. 

it  necessary  for  the  operator  to  do  this,  and  I  warn  you  against  the  practice 
with  the  same  feeling  that  I  would  cry  "Don't !"  if  I  should  see  you  mak- 
ing a  plaything  of  a  culture  of  the  bacillus  of  the  white  plague. 

Protection  lead  glass  spectacles  may  be  used  to 

Spectacles.  protect  the  eyes  (Fig.  321).     Not  because  the  eyes 

are  any  more  susceptible  to  the  ill  effects  of  the  X- 

rays  than  the  skin  of  the  face,  but  because  injury  to  them  is  such  a  serious 

matter.      Operators  suffering  from  chronic  dermatitis  of  the  face  usually 

suffer  also  impairment  of  vision. 

Protection   aprons  of  lead-impregnated    rubber 
Protection  may  be  purchased  from  manufacturers  of  X-ray  sup- 

flpron.  plies.    They  are  used  to  prevent  sterility. 

Protection  gloves,  spectacles  and  aprons  are  ob- 
viously not  needed  so  long  as  the  operator  remains  behind  a  screen. 

Having  now  told  you  of  the  dangers  of  the  X- 

Gfficiency  of  rays  and  shown  what  measures  have  been  adopted 

Protective  measures,     to  prevent  disaster,  the  question  arises,  Have  these 

modern  means  of  protection  proven  efficient? 

So  far  as  I  know,  no  man  who  has  conscientiously  and  consistently 

stayed  behind  a  protective  lead  screen,  or  in  a  lead  cabinet,  has  developed 

either  cancer  or  dermatitis  or  sterility,   or  suffered  or  experienced  any 

other  pathological  change  which  could  be  attributed  to  the  X-rays.     And 

some  have  been  engaged  in  the  work  for  as  long  as  twelve  years. 


THE   DANGERS   OE    THE   X-RAY  2S7 

The  severe  and  fatal  cases  of  dermatitis  and  cancer  have  occurred 
in  patients  who  received  prolonged  and  repeated  X-ray  treatments 
for  some  disease,  and  in  pioneer  operators. 

As  practitioners  of  dental  radiography,  we  will  never  be  called  upon 
to  make  such  exposures  of  our  patients  as  are  necessary  when  the  X-rays 
are  used  as  a  therapeutic  agent. 

The  pioneer  operators  whose  lives  were  ruined  and  destroyed  by  the 
X-rays  did  not  protect  themselves  at  all,  not  knowing  that  it  was  neces- 
sary. Even  without  any  protection  disaster  did  not  manifest  itself  imme- 
diately, as  might  be  imagined.  Men  worked  for  months  and  even  years 
before  any  trouble  developed.  Take  the  case  of  a  well-known  manu- 
facturer of  X-ray  tubes,  for  example.  He  exposed  himself  two  or  three 
hours  daily,  six  days  in  the  week,  for  a  little  over  a  year  before  he  no- 
ticed any  dermatitis.  It  must  be  remembered,  however,  that  at  that  time 
the  machines  and  tubes  could  not  generate  near  the  same  number  of  X- 
rays  that  the  improved  machines  and  tubes  of  to-day  can,  and  the  danger 
was  therefore  less. 

As  an  example  of  how  efficient  even  slight  protec- 

Cffictency  Of  tion  is,  Dr.  Porter  cites  a  case  of  dermatitis  of  the 

Slight  Protection.        hands,  save  for  the  skin  protected  by  a  broad  gold 
ring,    which    remained    perfectly   normal.     The    im- 
munity which  even  light  clothing  offers  is  shown  by  the  rarity  or  slight 
degrees  of  dermatitis  above  the  cuffs,  or  on  the  other  parts  of  the  body 
protected  by  clothing. 

Before  it  was  known  to  be  dangerous,  operators  formed  the  habit 
of  using  their  hands  for  penetrometers — observing  them  through  the  flu- 
oroscope  to  learn  the  power  of  penetration  of  the  X-rays.  This  prac- 
tice has  doubtless  caused  many  cases  of  dermatitis  and  cancer  of  the  back 
of  the  hands.  The  use  of  any  penetrometer  save  those  of  an  improved 
type  which  enable  the  operator  to  "look  around  a  corner"  necessitates  the 
exposure  of  the  operator,  especially  his  hands,  to  the  rays,  and  I  object 
to  their  use  for  this  reason. 

Summarizing  the  danger  to  the  operator,  we  may 
Summary  sa>'  simply  this:    If  he  will  observe  strictly  the  rule 

Of  Danger  to  remain  behind  a  lead  screen  or  in  a  lead  cabinet 

to  Operator.  he  may  work  for  a  period  of  ten  or  twelve  years  in 

safety.  What  the  dangers  of  exceeding  this  time 
limit  are  we  do  not  know.  Perhaps  there  are  none.  Perhaps  all  the  older 
X-ray  operators  will  die  of  leukemia  within  the  next  ten  years.  Who 
can  say  ?  We  are  entitled  to  our  opinions,  but  no  one  really  knows.  The 
pioneers  in  the  work  are  still  in  danger ;  we  who  follow  are  comparatively 
safe. 


DENTAL   RADIOGRAPHY 

Though  the  operator  need  never  expose  any  part  of  his  body  to  any 
except  the  weak,  harmless  X-rays  which  fill  the  room,  it  is  necessary  to 
expose  at  least  that  part  of  the  patient  being  radiographed  to  the  direct 
rays.  The  question  arises,  how  long  may  we  expose  the  patient  with 
perfect  safety,  without  any  danger  whatever  of  producing  acute  derma- 
titis ?     Authorities  are  very  reluctant  to  set  this  time  limit. 

The  very  few  cases  of  serious  acute  dermatitis  due  to  exposure  for 
radiographic  work  occurred  when  the  outfits  used  were  so  small  that  the 
time  of  exposure  reached  thirty  minutes  and  longer.  Compare  such  ex- 
posures with  those  of  to-day,  which  range  from  a  fraction  of  a  second  to 
only  one  minute  at  most,  even  with  the  small  suitcase  outfits,  and  the  im- 
probability of  producing  dermatitis  will  be  appreciated. 

The  first  rule  regarding  the  exposure  of  patients  should  be,  never  ex- 
pose the  patient  longer  than  absolutely  necessary. 

And  now  I  shall  place  myself  in  line  for  criti- 
time  Limit  for         cism  by  authorities,  by  setting  a  time  limit  of  ex- 
Cxposing  Patients,      posure  of  the  patient.     Even  with  the  smallest  appa- 
ratus, and  where  a  number  of  exposures  are  neces- 
sary, the  aggregate  time  of  exposure  need  not  and  should  not  exceed  two 
minutes.    If  it  is  necessary  to  use  this  full  time,  two  minutes  in  one  day, 
then  do  not  expose  the  same  part  of  the  same  patient  for  a  week  or  ten 
days.     Give  the  skin  a  chance  to  recover  from  any  change  produced  in 
it,  and  so  guard  against  a  cumulative  effect  of  the  X-rays.     I  cannot  im- 
agine a  case  in  dental  radiography  which  would  require  an  exposure  longer 
than  two  minutes.     And  seldom,   indeed,  will  it  be  found  necessary  to 
expose  the  patient,  even  in  the  aggregate  when  several  radiographs  are 
made,  as  long  as  the  time  limit  set. 

Two  minutes  is  a  conservative  limit — in  fact,  a  five-minute  exposure 
would  in  all  probabilities  prove  harmless — but  keeping  inside  of  it,  we  may 
have  the  assurance  that,  except  in  a  case  of  most  extraordinary  suscepti- 
bility, amounting  to  positive  idiosyncrasy,  nothing  more  than  a  very  slight 
acute  dermatitis,  no  worse  in  its  effect  on  the  health  and  happiness  of  the 
patient  than  a  mild  case  of  sunburn,  could  possibly  occur.  And  even  this 
slight  acute  dermatitis  is  so  extremely  unlikely  to  occur  that  the  careful 
operator  need  never  expect  to  see  it. 

Thus  I  may  say,  so  far  as  the  patient  is  con- 
Summary  of  cerned,  X-rays  are  perfectly  harmless  if  the  operator 
Danger  to  Patient.       is  careful.     The  danger  to  patients   from  infection 
by  instruments  is  infinitely  greater  than  the  danger 
from  the  sensible  use  of  the  X-rays  for  radiographic  purposes. 

"In  the  early  days  of  the  X-rays  there  was  a  tendency  to  attribute  X-ray 
burns  not  to  the  X-rays  themselves,  but  to  some  accompanying  factor,  the 


THE   DANGERS   OF    THE   X-k'AY  z$g 

exclusion  of  which  would  prevent  the  occurrence  of  X-ray  burns."*  Thus  it 
was  suggested  that  burns  were  due  to  an  electrical  condition  surrounding 
the  tube;  to  chemical  conditions  surrounding  the  tube;  to  bacteria  being 
carried  into  the  tissues  by  the  X-rays ;  to  violet  rays,  and  so  on.  It  is  gen- 
erally conceded  to-day,  however,  that  X-ray  burns  are  the  result  of  a  spe- 
cific action  of  the  X-rays  themselves  on  the  tissues. 

There  is  a  popular  theory  that  for  X-rays  to 

Cbe  Tilter.  have  an  effect  on  the  skin  they  must  be  absorbed  by 

it.  Thus,  the  more  penetrating  X-rays  which  pass 
completely  through  the  derma  are  less  likely  to  produce  dermatitis  than 
rays  of  less  penetration — just  enough  penetration  to  be  absorbed.  Know- 
ing this  theory — a  theory  the  writer  receives  with  skepticism — we  will  now 
consider  the  use  of  a  filter. 

First,  however,  let  us  dwell  on  some  points  which  were  not  touched 
upon  in  Chapter  III,  when  we  discussed  the  generation  and  nature  of 
X-rays.  It  was  stated  in  Chapter  III  that  the  X-rays  from  a  tube  of  high 
vacuum  were  the  most  penetrating — that  the  penetration  of  the  X-rays 
varied  directly  according  to  the  degree  of  vacuum  of  the  tube.  Thus  the 
X-rays  from  a  high  vacuum  tube  are  very  penetrating,  the  rays  from  a 
medium  vacuum  tube  of  medium  penetration,  and  the  rays  from  a  tube 
of  low  vacuum,  of  low  penetration.  While  this  is  true,  there  is  something 
further  to  be  said.  Take  the  high  vacuum  tube :  while  most  of  the  di- 
rect X-ray  given  off  from  it  are  of  high  penetration,  some  rays  of  me- 
dium and  low  penetration  are  also  generated.  While  the  tube  of  medium 
vacuum  generates  X-rays  of  medium  penetration  principally,  some  rays 
of  high  and  low  penetration  are  also  generated ;  and  though  the  X-rays 
from  a  tube  of  low  vacuum  are  by  far  mostly  of  low  penetration,  some  few 
rays  of  medium  and  high  penetration  are  given  off  also. 

Since  the  tube  of  a  high  vacuum  is  the  one  we  use  in  radiographic 
work,  let  us  enumerate  the  different  sets  of  X-rays  given  off  from  such  a 
tube.  First,  are  the  direct  rays  of  high  penetration — these  are  by  far 
the  most  numerous ;  next,  the  sets  of  direct  X-rays  of  medium  and  low 
penetration — these  are  comparatively  few  in  number;  then  secondary  X- 
rays  given  off  from  the  glass  of  the  tube;  and  last,  if  there  is  any  in- 
verse current  in  the  tube,  the  rays  generated  by  it. 

If  now  the  theory  of  absorption  for  effect  is  correct,  then  it  is  de- 
sirable to  expose  the  patient  only  to  the  direct  penetrating  X-rays,  and  not 
to  any  of  a  less  penetrating  nature.  In  an  effort  to  gain  this  end  the 
filter  is  used. 

Filters  are  made  of  wood,  aluminum,  leather  and  various  other  ma- 
terials.    For  example,  a  piece  of  sole  leather  (no  definite  thickness)    is 


*Pusley  and  Caldwell,  "Roentgen  Rays  in   Therapeutics  and  Diagnosis. 


290  DENTAL  RADIOGRAPHY 

placed  over  the  window  of  the  tube  shield.  The  X-rays  from  the  tube 
pass  through  it  before  striking  the  patient  and  the  leather  filters  out,  ab- 
sorbs, all  (?)  of  the  weaker  rays,  which  might  otherwise  be  absorbed  by 
the  skin,  and  so  guards  against  dermatitis. 

The  danger  of  producing  dermatitis  varies  directly  according  to  the 
number  of  X-rays  which  strike  the  part.  Recollect  that  X-rays  emanate 
from  a  point,  traveling  in  diverging  lines.  Thus  the  greater  the  distance  be- 
tween the  target  and  the  skin  the  fewer  rays  strike  the  latter  and  the  less 
danger  of  dermatitis.  When  the  tube  is  brought  very  close  (within  three 
or  four  inches)  to  the  part  and  no  filter  is  used  the  skin  is  then  acted  upon 
not  only  by  a  much  greater  number  of  the  direct  penetrating  rays,  but  also 
by  the  softer  direct  rays  and  by  the  secondary  rays  from  the  glass  of  the 
tube,  so  increasing  the  danger  of  burning  materially.  Thus  it  will  be  seen 
that  the  use  of  the  filter  permits  the  operator  to  place  the  tube  close  to  the 
patient,  so  that  his  film  or  plate  is  within  range  of  a  greater  number  of 
penetrating  direct  rays,  and  at  the  same  time  protects  the  patient  against 
the  soft  rays.  (See  summary  of  the  conditions  under  which  Fig.  121 
was  made,  Chapter  V.) 

Theoretically,  the  use  of  the  filter  should  aid  in  obtaining  a  clear 
radiograph  by  cutting  out  all  save  the  direct  penetrating  rays.  It  is  not 
as  efficient  in  this  respect,  however,  as  the  compression  diaphragm.  (Figs. 
60  and  66.) 

The  number  of  direct  X-rays  generated  by  a  given  tube  varies  di- 
rectly according  to  the  number  of  milliamperes  sent  through  it.  Thus 
danger  of  dermatitis  also  varies  directly  according  to  the  number  of  mil- 
liamperes sent  through  the  tube.  To  elucidate:  the  distance  between  the 
tube  and  the  skin  remaining  the  same,  an  exposure  of  one  minute  with 
ten  milliamperes  passing  through  the  tube  will  have  practically  the  same 
physiologic  effect  as  an  exposure  of  two  minutes  with  five  milliamperes 
passing  through  the  tube. 

There  is  no  such  thing  known  as  either  acquired 

Immunity.  or    natural    immunity  to  the  action  of  the  X-rays. 

Some  are  more  susceptible  than  others,  but  no  one 

is  immune.     Blondes  are  reputed  to  be  more  susceptible  than  brunettes. 

'  >ne  burn  greatly  predisposes  to  another. 

The  careful  practitioner  of  dental  radiography, 
treatment  of  unless  he  meets  a  case  of  idiosyncrasy,  will  never 

Acute  X-Ray  have  occasion  to  make  use  of  knowledge  regarding 

Dermatitis.  the  treatment  of  acute  X-ray  dermatitis.     It  is  well, 

however,  to  have  the  knowledge  even  though  we  are 
never  called  upon  to  use  it.  The  most  important  thing  to  know  concern- 
ing the  treatment  of  acute  X-ray  burns  may  be  learned  from  the  nursery 


THE  DANGERS  OF   THE  X-RAY  291 

rhyme  about  "Little  Bo-Peep"  and  "her  sheep."  "Let  them  alone."  So 
many  drugs  aggravate  the  condition  that  their  use  is  contraindicated.  A 
normal  salt  solution  is,  perhaps,  the  best  wash  and  may  be  used  freely. 

There  will  be  men  in  our  profession  who  will  not  take  up  radiographic 
work,  and  who  will  say  as  an  excuse  for  not  doing  so  that  they  believe 
the  work  "too  dangerous."  Men  who  give  this  excuse  are  either  unac- 
quainted with  the  facts  relative  to  the  real  danger  or  they  are  deceiving 
themselves.  A  disinclination  to  do  necessary  work,  mental  and  physical, 
may  lead  a  man  to  believe  that  the  reason  he  does  not  take  up  X-ray  work 
is  because  he  believes  it  to  be  "dangerous." 

It  is  interesting  to  know  that  the  rays  given  off 
Radium  by  the  recently  discovered  element  radium  are  very 

Ray$.  similar  to  the  X-rays. 

The  commercial,  so-called,  radium  is  not  pure 
radium.  It  is  a  salt  of  radium,  usually  radium  bromid.  So  far,  radium 
never  has  been  isolated.     Radium  bromid  is  a  white  crystal. 

"In  1896  it  was  discovered  that  the  metal  uranium  gave  off  rays  very 
similar  to  X-rays.  Observing  that  different  pieces  of  uranium  varied 
greatly  in  their  radio-activity,  M.  and  Mme.  Curie,  of  Paris,  working  on 
the  hypothesis  that  uranium  itself  was  not  radio-active  at  all,  but  derived 
this  property  from  some  impurity  incorporated  in  it,  isolated  radium 
bromid  from  the  metal  uranium."* 

At  present  radium  salts  are  obtained  from  uranium  oxid,  which  lat- 
ter is  first  obtained  from  pitchblende,  a  heavy  black  material  in  appearance 
somewhat  similar  to  anthracite  coal.  One  ton  of  pitchblende  must  be 
treated  with  approximately  five  tons  of  various  chemicals  and  fifty  tons 
of  water  to  obtain  one  gram  of  radium  bromid.  The  present  market  price 
of  one  gram  of  radium  bromid  ranges  from  $1,500  to  $125,000,  according 
to  the  radio-activity  of  the  salt. 

Radium  rays,  like  X-rays,  cannot  be  reflected  or  refracted.  They 
travel  in  straight  lines,  and  secondary  rays  are  given  off  from  objects 
which  they  strike.  They  penetrate  objects  directly  according  to  the 
density  of  the  object,  and  act  on  a  photographic  plate  like  light  and  X-rays. 
Their  physiologic  effect  on  the  skin  is  very  similar  to  X-rays.  They  pro- 
duce a  dermatitis  almost  identical  to  X-ray  dermatitis.  Becquerel  carried 
a  sealed  glass  tube  containing  0.2  gram  of  radium  salt  in  his  shirt  pocket 
for  six  hours.  Fifteen  days  thereafter  a  dermatitis  closely  simulating 
X-ray  dermatitis  appeared,  then  subsided  in  about  thirty  days.  One  case 
of  fatality  from  leukemia  caused,  presumably,  by  radium  has  been  re- 
ported. 


"Tousey,  "Medical  Electricity  and  Roentgen  Rays. 


CHAPTER    IX 

Purchasing  a  Radiograph  Outfit. 

Before  considering  the  purchase  of  a  radiographic  outfit  we  would 
better  settle  the  question  of  who  should  do  dental  radiographic  work. 
Should  it  be  done  by  specialists  or  the  general  practitioners  of  dentistry? 
Three  years  ago  it  was  my  habit  to  answer  this  question  unhesitatingly, 
and  say  "by  the  specialist." 

My  reasons  for  believing  that  dental  radiographic  work  should  be 
done  by  specialists  were :  ( i)  I  was  of  the  opinion  that  the  radiograph  was 
not  particularly  useful  in  the  practice  of  dentistry  except  in  rare  cases, 
ami  i  2)  there  being  no  text-book  on  the  subject,  proper  self-education  in 
the  art  was  difficult,  almost  to  the  point  of  being  impossible. 

As  1  see  the  situation  to-day,  however,  the  use  of  the  radiograph  is 
indicated  in  so  many  cases  that  it  would  be  rather  impracticable  for  the 
general  practitioner  to  refer  all  radiographic  cases  to  the  specialist.  A 
further  objection  to  referring  all  radiographic  cases  to  the  specialist  is 
that,  while  said  specialist  may  be  a  very  expert  radiographer,  his  knowl- 
edge regarding  dental  subjects  may  be  so  meagre  that  he  cannot  interpret 
the  radiograph  correctly  after  it  is  made.  Notwithstanding  these  draw- 
backs to  the  practice  of  referring  patients,  1  can  understand  the  attitude 
of  the  busy  city  dentist,  who  does  not  care  for,  or  dislikes  radiographic 
work,  and  therefore  would  prefer  to  refer  his  cases  to  a  dental  radio- 
graphic specialist. 

But  no  matter  how  busy  he  may  be  nor  how  much  he  may  dislike 
the  work,  the  dentist  in  the  smaller  cities  and  towns,  where  there  is  no 
specialist  in  the  same  town,  should  be  able  to  do  at  least  the  simpler 
radiographic  work  on  films  himself.  Otherwise  the  work  will  not  be 
done  at  all,  because  of  the  inconvenience  incident  to  making  a  trip  to 
the  city  specialists,  and  in  consequence  the  best  dental  services  will  not 
be  rendered.  It  is  an  exceptional  case  indeed  when  a  general  practi- 
tioner of  dentistry  develops  a  degree  of  skill  and  proficiency  equal  to 
that  attained  by  the  specialists-^-  the  man  who  devotes  all  of  his  time  to 

202 


PURCHASING  A   RADIOGRAPH   OUTFIT  293 

radiographic  work — and  the  more  difficult  work  on  large  plates,  neces- 
sitating a  pose  in  the  recumbent  position,  and  stereoscopic  work  should 
therefore  better  be  referred  to  specialists. 

My  second  reason  for  having  formerly  been  of  the  opinion  that  all 
radiographic  work  should  be  referred  to  specialists — viz.,  the  difficulty  of 
self-education — I  hope  is  no  longer  a  good  reason,  for  I  have  tried,  in 
this  work,  to  supply  a  text-book  which  will  enable  the  man  who  wishes  to 
take  up  dental  radiography  to  do  so  without  wasting  a  great  deal  of 
time  and  energy  reading  books  on  electricity,  photography  and  general 
X-ray  work. 

Some  manufacturers  make  such  statements  regarding  radiographic 
work  as,  "The  work  is  extremely  simple  and  can  be  mastered  in  a  few 
minutes ;  in  the  time  it  will  take  to  glance  over  our  instructions  which 
we  send  with  each  outfit."  As  a  result  of  such  misrepresentation  men 
have  taken  up  the  work  in  profound  ignorance  and  so  have  endangered 
their  own  and  their  patient's  health  and  life.  Self-education  to  do  the 
simplest  work  intelligently,  safely  and  well  is  not,  I  assure  you,  a  matter 
of  a  few  minutes  study,  but  of  many  hours. 

In  passing  let  me  mention  X-rays  as  a  thera- 
X-Ravs  peutic  agent  in  dentistry,  and  condemn  them  as  use- 

as  a  less.     It  is  so  difficult  to  measure  the  dose  in  X-ra- 

Chcrapcutic  diation  that  it  is  only  by  long  and  usually  soul-trying 

•"9en*'  and  disastrous  experience  that  a  man  becomes  com- 

petent to  use  X-rays  as  a  therapeutic  agent.  The 
work  should  be  done  by  specialists  only.  General  practitioners  of  either 
dentistry  or  medicine  are  liable  to  do  more  harm  than  good  when  at- 
tempting therapeutic  X-radiation. 

X-rays  have  been  employed  in  the  treatment  of  pyorrhoea  alveolaris, 
but  no  results  have  been  obtained  that  have  not  been  gained  by  the  use 
of  the  easier  used,  better  known,  less  dangerous  drugs,  commonly  applied. 
The  incurable  cases  remain  incurable,  whether  the  X-rays  are  used  or 
not,  and,  in  the  cases  in  which  disease  is  due  to  local  irritants  which  can 
be  removed,  recovery  takes  place  as  a  result  of  the  universally  known 
methods  of  treatment — again,  whether  the  X-rays  are  used  or  not. 
X-rays  are  used  also  for  the  treatment  of  cancer  of  the  mouth  and 
leukoplakia,  but  such  diseases  are  comparatively  rare  and  if  treated  with 
the  X-rays,  the  work  should  be  done  by  specialists.  As  far  as  I  know, 
this  is  the  extent  of  the  therapeutic  application  of  the  X-rays  to  diseases 
of  the  mouth — an  extremely  limited  application. 

In  short,  my  opinion  of  the  value  of  the  X-rays  in  the  practice  of 
dentistry  is  this:  as  a  means  of  making  dental  radiographs  they  are  in- 
valuable ;  as  a  therapeutic  agent,  they  are  worse  than  useless. 


294  DENTAL   RADIOGRAPHY 

Of  what  should  a  dental  radiographic  outfit  con- 
Rcquircmcnts  s'st"'     Gaining  the  hare  necessities  for  the  simplest 

of  a  Radiographic        work — to  which  the  operator  may  add,  as  he  does 
Outfit,  the  work  and  feels  the  need  of  expediting  apparatus 

—we  have  :  ( i )  Photographic  paraphernalia  and  sup- 
plies, including  a  dark-room  lantern,  trays,  a  glass  graduate,  prepared 
developing  powder  or  solution,  prepared  fixing  powder,  and  films;  (2)  an 
X-ray  machine  or  coil;  (3)  an  X-ray  tube;  (4)  a  tube  stand;  (5)  a  lead 
screen. 

All  the  photographic  paraphernalia  and  supplies,  except  the  films, 
may  be  purchased  at  any  photographic  supply  house.  Regarding  films 
see  page  85.  Regarding  the  dark-room  lantern  see  page  68.  Regarding 
developing  solutions  see  pages  75,  76,  102  and  103.  Regarding  fixing 
solutions  see  pages  78  and  104.  The  expenditures  for  photographic  para- 
phernalia and  supplies  need  not  exceed  $5  at  most. 

There  are  three  kinds  of  X-ray  machines  for  the  prospective  buyer 
to  choose  from:  the  transformer  or  interrupterless  coil  (Figs.  15  and  38), 
the  induction  coil   (Fig.  13),  and  the  high  frequency  coil  (Fig.  14). 

The    transformers   are   the   most   powerful   and 
Tntcrruptcrless  most    expensive    X-ray    machines    on    the    market. 

Coils.  With  them  small,  film  radiographs  may  be  made  in 

an  exposure  of  one  second  or  fraction  thereof.  The 
finished  radiograph  from  such  an  exposure  is  no  better  than  one  made 
with  a  less  powerful  machine  from  a  longer  exposure.  Personally,  1  can 
see  no  particular  advantage  in  shortening  the  exposure  beyond  two  or 
three  seconds.  The  transformer  is  for  the  specialist  or  general  practi- 
tioner who  is  fortunate  enough  not  to  have  to  consider  seriously  the 
expenditure  of  a  considerable  amount  of  money.  Transformers  range  in 
cost  from  six  hundred  to  over  a  thousand  dollars. 

See  summary  of  conditions  under  which  Fig.   117  was  made,  page 

Induction  coils  are  marie  in  various  sizes.  The  largest  ones  rival 
the  transformers  in  power,  the  smaller  ones  are  not  nearly  so  powerful. 

summaries  of  conditions  under  which  Figs.  81,  in,  97,  99,  103,  100, 
105,   11N.   110.   [20  and   12]    were  made. 

Induction  coils  range  in  price  from  about  $200 
Induction  to  $600. 

CoiU.  Unless   he   need   not    consider   the   expenditure 

of  money  I  would  advise  the  general  practitioner  of 


PURCHASIXG   A   RADIOGRAPH   OUTFIT  295 

dentistry  who  wishes  to  do  only  the  lighter,  simpler  work  on  films  to 
l)ii\'  either  a  small  induction  coil  or  one  of  the  hest  high-frequency,  suit- 
case coils.  If  his  supply  current  is  direct,  I  would  say  choose  the  induc- 
tion coil;  if  alternating,  the  high  frequency  coil.  My  reason  for  this 
discrimination  is  that  when  the  induction  coil  is  operated  on  an  A.  C. 
ciicuit  the  current  must  first  be  passed  through  a  rectifier  (Figs.  27 
and  28).  The  purchase  of  the  rectifier  adds  to  the  expenditure,  and  its 
use  detracts  from  the  efficiency  of  the  coil.  When  the  high-frequency 
coil  is  used  on  the  D.  C.  circuit  a  rotary  converter  (Fig.  36)  must  be 
used.  This  also  adds  to  the  expenditure  and  cuts  down  the  efficiency  of 
the  coil.  Some  suitcase  coils  are  advertised  to  operate  on  either  a  direct 
or  alternating  current,  without  a  rotary  converter  for  the  latter.  A 
vibrator  interrupter  (Fig.  22)  is  used  on  these  machines.  Less  efficiency 
is  lost  with  the  rotary  converter  than  with  the  vibrating  interrupter. 

Most  high   frequency,   suitcase,  X-ray   coils  are 
fiigb   frequency         built   to    sell ;   not   to   make    radiographs.     Only   the 
Coils.  most  powerful  of  the  type  are  capable  of  doing  good 

dental  radiographic  work.  1  would  advise  the 
prospective  purchaser  to  insist  on  a  practical  demonstration  before  in- 
vesting. What  may  be  expected  from  the  more  powerful  of  these  coils 
may  be  learned  from  the  study  of  the  summaries  of  the  conditions  under 
which  Figs.  112,  113,  114  and  115  were  made. 

The  high  frequency  X-ray  coils  range  in  price  from  about  $150  to 
$200. 

A  six-inch  X-ray  tube  is  the  proper  size  to  do 

X-Ray  dental   radiographic   work.      Only  the  tubes   with   a 

Cubes.  regulating    chamber    are    popular    to-day    (see    Fig. 

44).     The  price  of  the  six-inch  X-ray  tube  is  well 

standardized  and  is  $20. 

There    are    a   great    variety    of    tube    stands   to 
Cube  choose    from     (Figs.    59,    60,    61    and    63).     They 

Stands.  range  in  price  from  $10  to  $150.     The  small  tube 

stands  or  holders  which  are  fastened  onto  the  suit- 
case coils  do  not  permit  of  a  sufficient  range  of  movement  to  adjust  the 
tube  properly,  nor  are  they  substantial  enough  to  hold  the  tube  firmly 
immovable. 

Lead   screens    (Figs.   314  and   315)    cost    from 

Protection  $10  to  $30.    Even  the  best  lead  screens  are  not  backed 

Screens.  with    lead    thicker    than     1/16    inch.     The     writer 

operates  back  of  a  "home-made"  screen  the  lead  of 

which  is  T/s  inch  thick  and  the  3x3  inch  window  the  lead  glass  of  which 


296  DENTAL    RADIOGRAPHY 

is  1 3  _  inches  thick.  The  material  for  this  screen  cost  $15.  It  is  not  a 
particularly  beautiful  piece  of  furniture,  and  if  the  time  spent  in  building 
it  be  considered  worth  anything,  1  did  not  save  money,  but  the  finished 
streen  offers  more  protection  than  any  1  know  of  on  the  market. 

A  man  may  figure  from  the  foregoing  approximately  what  it  will 
cost  him  to  buy  the  kind  of  an  outfit  he  wishes  to  purchase. 

Let  us  take  a  concrete  example  of  a  general  practitioner  who  wishes 
to  make  the  minimum  investment  and  obtain  an  outfit  with  which  he 
may  do  the  lighter  work  on  films,  and  perhaps  occasionally  make  a  large 
plate  radiograph.  His  photographic  paraphernalia  costs  say  $4.  As- 
suming that  his  supply  current  is  A.  C,  he  may  purchase  a  high  frequency 
radiographic  coil  for  $150.  An  X-ray  tube  costs  $20,  a  tube  stand  $12. 
He  makes  his  own  screen  the  material  for  which  costs  $15.  He  spends 
$201  and  has  an  outfit  with  which  he  can  make  small  film  radiographs 
in  a  10  to  20  second  exposure  and  large  plate  radiographs  in  about  one 
minute. 


CHAPTER  X. 

Stereoscopic  Radiography. 

The  word  stereoscopic  is  derived  from  two  Greek  words,  meaning 
"solid"  and  "to  see." 


Fig.   322.      Hand   stereoscope   in   use. 

The  phenomenon  of  the  stereoscopic  picture  or  radiograph  is  one 
very  difficult  to  explain  briefly.  It  is  sufficient  for  us  to  say  here  that  to 
gain  a  stereoscopic  effect — that  is.  to  get  a  picture  rich  in  perspective — 
we  must  have  two  pictures,  one  for  each  eye,  and  observe  them  with  a 
stereoscope  (Figs.  322  and  323).'  When  the  two  pictures  are  properly 
focused  in  the  stereoscope,  the  observer  no  longer  sees  two  flat  pictures 
of  the  same  object,  but,  instead,  the  single  object  stands  out  in  clear 
perspective,  just  as  it  would  if  we  looked  at  the  object  itself,  the  two 
pictures  being  registered  on  the  retina  of  either  eye  and  the  merging  centre 
of  the  brain  fusing  them  into  one. 


-?97 


_•■  .s 


DENTAL   RADIOGRAPHY 


To  make  stereophotographs  it  is  necessary  to  use  a  special,  double- 
lens  camera  ( Fig.  324 ) .  which  takes  a  picture  for  each  eye  simultaneously. 
Figs.  2,37  and  338  are  stereophotographs. 

A  moment's  consideration  of  the  subject  makes  it  obvious  that  two 
radiographs,  one  for  each  eye,  cannot  be  made  simultaneously.    We  must 


Fig.    .'!23.     Large   stereoscope   made   especially    for   observing   stereoradiographs. 


place  the  X-ray  tube  in  the  position  to  make  the  radiograph  for  one  eye 
and  make  the  exposure,  then  shift  the  tube  two  and  one-half  inches  (the 
approximate  distance  between  the  eyes),  place  a  new  plate  or  film  in 
tly  the  same  position  occupied  by  the  first  plate  or  film  (and  this 
without  changing  the  position  of  the  part  being  radiographed),  and  make 
a  second  exposure  to  get  the  radiograph  for  the  other  eye. 

To  accomplish  the  proper  shifting  of  the  tube  a 

Stereoscopic  special  tube  stand  or  pedestal  should  be  used.   There 

tube  Stand.  arc-    several    such    stands    on    the    market   known    as 

"stereoscopic  tube  stands."    The  one  shown  in  Fig. 

61,  and  again  in  Figs.  326  and  330,  is  used  by  the  writer. 


STEREOSCOPIC   RADIOGRAPHY 


299 


To   accomplish    the    removal    of   the   first   plate 
Plate  after  exposure,  and  replace  it  with  a  second  plate 

€b<ingcr$.  for    the    second    radiograph,    without    changing   the 

position  of  the  part  being  radiographed,  it  is  neces- 
sary to  use  a  plate  changer  (Fig.  325),  or  a  "stereoscopic  table"   (Fig. 


Fig.    324.      Double   lens   camera    for   making  stereophotographs. 


Fig.    325.      Piatt   changer. 


326),  which  latter  is  simply  a  large  plate  changer  made  into  a  table.  The 
principle  of  all  plate  changers  is  the  same.  The  part  being  radiographed 
rests  undisturbed  on  a  window  of  celluloid  or  thin  aluminum,  while  the 
plates  slide  beneath  in  a  tunnel. 


DEXTAL   RADIOGRAPHY 


Fig.   320.     Stereoscopic   tabic   and   tube  stand.     II,   centering  rod. 


The  plate  changer  illustrated  in  Fig.  330,  and  explained  by  diagram  in 
Fig.  327,  differs  from  others  in  that  only  one  five  by  seven  inch  plate 
is  used,  two  pictures,  five  by  three  and  one-half  inches,  being  made  on 
either  end  of  the  plate.  A  five  by  seven  stereoradiograph  (both  pictures 
on  the  one  plate)  may  be  observed  with  a  hand  stereoscope  (Fig.  322), 
while  all  other  plate  stereofadiographs  must  he  observed  with  the  special 
stereoscope  (Fig.  323). 


STEREOSCOPIC   RADIOGRAPHY 
I  J 


301 


->o 


Cv      AA 


g  y   y    V  y  y\  x  y  \v   x  x  v  x  x  x  xitxt 


xn-3 


Fig.  327.  A  and  AA,  lead  which  protects  the  plate  against  the  action  of  the  X-ray.  B,  window 
of  thin  aluminum  or  celluloid  on  which  the  part  being  radiographed  lies.  C,  end  of  the  tunnel. 
D,  plate  carrier.  E,  end  of  5x7  plate  on  which  the  first  radiograph  is  made  with  the  tube  in 
position  I.  EE,  end  of  plate  on  which  second  radiograph  is  made  after  it  is  shifted  under 
the   window    B,   and  the   tube   is   in   position  J.      F,   centering   line.      G,   angle    of   X-rays   with   the 

tube   in   the   first   position.    I.      H,    angle   of    X-rays   with   the   tube    in   second   position,   J. 

The   diagram   shows   the   tube   being   shifted    on   a   line   with    its   long   axis.      It   may   be   shifted    in 

this    manner,    or    at    any    angle    to    its    long    axis — it    makes    no    difference. 


Fig.    328.     Compression   cones,    cylinder   and    square. 


302  DENTAL   RADIOGRAPHY 

tecbnic  for  makins  Stereoradiography. 

Let  us  now  take  a  concrete  example  and  describe  and  discuss  the 
steps  taken  in  the  making  of  Fig.  339. 

First,  what  should  be  the  distance  between  the 
Distance.  target  and  the  plate?    There  are  no  special  rules  to 

follow  regulating  the  distance  between  the  target  and 
the  plate  when  making  stereoradiographs.  The  same  results  were  ob- 
tained by  the  writer  with  the  distance  twelve  inches  as  when  working 
at  twenty-four  inches. 


Fig.    329.      The   lead   glass   bowl   and    X-ray    tube    must   be    removed    while    the    centering    rod    is 
'jeing  used.      When  the  stand   is   "set,"   the   rod   is   removed  and  the  protection    bowl   and    X-ray 

tube    replaced. 

The  first  step  is  to  "centre  the  tube."  to  place  it 

Setting  so  that  a  line  (line  F  of  Fig.  327)  drawn  from  the 

tube  Stand.  focal  point  on  the  target  will  strike  the  plate  in  the 

center.    This  may  be  done  with  the  greatest  accuracy 

by  the  use  of  the  centering  rod   (Fig.  326),  but  the  use  of  the  rod  is 

not  imperative  unless  a  compression  cone  or  cylinder  (Fig.  328)  is  to  be 

used,  as  will  be  described  presently. 

After  centering  the  tube,  when  using  a  stand  like  the  one  in  Figs. 
326  and  330,  the  stand  is  "set"  so  that  the  tube  may  be  moved  one  and 
one-quarter  inch  on  each  side  of  the  center  to  positions  I  and  J  of 
Fig.  327  (see  illustration). 


STEREOSCOPIC  RA  1)1  OCR.  IPHY 


303 


Fig.    330.      Pose    for   making    Fig.    344.      It   is    often    expedient   to    have    the    patient    remove    the 

coat    and    collar    for    this    pose. 


3°4 


DENTAL    RADIOGRAPHY 


Fig.    331.      Modified    Kny-Sheerer    film    holder. 


Fig.    332.      The    film    holder   shown    in    Fig.    331    in    position. 


l"ig.   888.     Another  view   <<f   the  film   holder   in   position. 


STEREOSCOPIC   RADIOGRAPHY  305 

[t  is  not  necessary  to  tip  the  tube,  as  it  is  shifted. 

tipping  in  order  to  have  the  X-rays  strike  the  object  and 

thi  Cube.  plate  at  the  proper  angles — at  the  angles  at  which  the 

eyes  of  an  observer  would  see  the  object,  because  the 

X-rays  emanate  from  the  focal  point  on  the  target  in  diverging  lines  in  all 

directions.     So  the  same  X-rays  are  not  used  to  make  the  second  picture 

that  are  used  to  make  the  first.     If  they  were,  it  would  be  necessary  to 

tip  the  tube  to  make  them  strike  the  object  and  the  plate  at  the  proper 

angles.     (Observe  lines  G  and  H  of  Fig.  $2j.)     When  using  a  compres- 


Fig.   334  Fig.   335  Fig.   336 

Fig.    334.      The    photographic    print    from    which    this    halftone    was    taken    was    made    from    the 

original   negative,   or   "first   picture." 
Fig.    335.      The    same    as    Fig.    334,    except    made    from    "pictures    one    and    two,"    held    together 

with    binding    strips. 
Fig.   336.     The  same   field  as    Fig.   334,   but   made   from   the   "third  picture." 

sion  cone  or  cylinder  we  do  use  the  same  rays  to  make  both  radiographs, 
and  hence  it  becomes  necessary  to  tip  the  tube  as  it  is  shifted.  This  can 
be  accomplished  with  accuracy  only  by  the  use  of  the  centering  rod  (see 
Fig.  329).  Thus,  if  a  cone  or  cylinder  is  to  be  used,  the  tube  stand  must 
be  "set"  not  only  to  shift  the  tube  but  to  tip  it  also  as  it  is  shifted. 

With  the  tube  stand  "set.'*  the  tube  in  position  I  of  Fig.  327,  and  the 
plate  in  the  position  shown  in  Fig.  327,  the  first  exposure  is  made.  The 
tube  is  then  shifted  to  position  J,  the  plate  carrier  pushed  in  until  the 
unexposed  half  of  the  plate  comes  under  the  window  B,  and  the  second 
exposure  is  made.  Since  the  two  radiographs  are  made  on  the  same  plate 
in  this  instance,  special  care  should  be  taken  to  expose  them  each  the 
same  length  of  time.  Otherwise  they  will  "come  up"  unequally  in  the 
developing  solution  and  radiographs  of  different  densities  will  result. 

If  the  technic  outlined  above  is  followed,  it  will  be  found  when 
observing  the  finished  stereoradiograph  that  we  see  the  part  from 
the  position  of  the  tube  during  exposure.  Thus  observe  Fig.  339.  which 
was  taken  with  the  palm  of  the  hand  toward  the  plate,  a  coin  on  the 
back  of  the  hand,  a  needle  under  the  hand. 

If.  instead  of  following  the  technic  as  given,  the  first  exposure  be 
made  with  the  tube  in  position  J  and  the  plate  as  shown  in  Fig.  327, 
and  the  second  exposure  with  the  tube  in  position  I.  after  the  plate  is 
shifted ;    then,    when   observing   the    finished    stereoradiograph.    it    is    as 


3'  >' ' 


DENTAL    RADIOGRAPHY 


Sten  tograpb    of    the    skull    of   a    monkey,    from    Dr.    John    J.    Kyle's    collection    of 

skulls    of    vertebrates. 

though    we    saw    the    part    from    the    position    of    the    plate    during    its 
exposure  (see  Fig.  340;. 

This  changing  of  position  of  observation  may  be  accomplished  also 
by  interchanging  the  two  radiographs — placing  the  right  on  the  left  and 
the  left  on  the  right.  Take  Fig.  339.  for  example ;  interchange  the  radio- 
graphs and  the  stereoradiograph  is  the  same  as  Fig.  340;  or  take  Fig. 
340  and  interchange  the  radiographs  and  the  stereoradiograph  is  the  same 
as  Fig.  339.  The  interchanging  of  radiographs  must  be  done  without 
inverting  them,  or  the  change  of  position  of  observation  will  not  be  ac- 
complished— the  stereoscopic  effect  will  remain  the  same  and  the  part  will 
-imply  be  viewed  upside  down. 


tion    of    the    skull    of    a    monkey,    from     l)r.    John    J.     K  'ion    of 

skulls    of 


STEREOSC  OPIC   K.  UROGRAPHY 


307 


Fig.    339.      Showing   the   coin   on    one   side   of   the   hand,   the    needle    on    the   other.      Here    we   ob- 
serve   the    hand    from    the    position    of    the    tube. 


Fig.   340.     The  same  as  Fig.  339  except  that  we  observe  the  hand  from  the  position  of  the  plate 
during   its   exposure,   instead   of   the   position   of   the    X-ray    tube. 


DENTAL   RADIOGRAPHY 


II.     Three    nails    of    the    same    size    and    length.     One    is    in    a    vertical    position,    the    other 
two  lean   toward  the   observer,   at   different   angles. 

Figs.  341.  342  and  343  are  the  same  radiographs  mounted  differently. 
No  stereoscopic  effect  at  all  is  seen  in  Fig.  343,  because  the  tube  was 
shifted  at  right  angles  to  the  long  axis  of  the  nails.  Had  the  tube  been 
shifted  on  a  line  with  the  long  axis  of  the  nails  it  would  be  necessary  to 
observe  them  as  in  Fig.  343  to  get  a  stereoscopic  effect. 


B 


1  he  same  a*    Kig.   .".ii    except   thai    the   individual    radiograph!   are    interchanged,   tin- 
right   changed    to  the   left   lide   and    the    left    to   the    ri«ht    side.     Thus   in    this   stereoradiograph 
the   leaning   nails   lean    away    from    instead    >>f   toward    the    observer. 


STEREOSCOPIC   RADIOGRAPHY 


3<*j 


Fig.  343.     No  stereoscopic  effect  at  all  is  obtained  with  the  radiographs  mounted  as  in  this  figure. 


We  now  come  to  a  more  definite  consideration 
of  dental  stereoscopic  radiography.  Stereoradio- 
graphy of  the  lower  teeth  may  be  made  on  plates 
using  the  plate  changer  illustrated  in  Fig.  327.  Fig. 
344  is  such  a  stereoradiograph.  Fig.  344  was  made 
from  the  pose  illustrated  in  Fig.  330. 


Special  teebnic 
for  Dental  Stereo- 
Radiography. 


Fig.   344.     Though  the  stereoscopic  effect  is  not  very   good  the  figure   is   representative   of   what 
can    be   done    by    the    method    employed    to    make    this    stereoradiograph. 


3io  DENTAL    RADIOGRAPHY 

When  making  stereoradiographs  on  separate  plates,  like  Figs.  345 
and  340.  it  is  necessary  to  use  a  large  plate  changer,  like  Figs.  325  and  326. 
Figs.  345  and  34(1  were  made  on  eight  by  ten  inch  plates,  and  the  radio- 
graphs reduced  as  shown  in  the  figures,  so  that  they  might  he  observed 
with  the  small  hand  stereoscope.  To  observe  the  original  negatives  it  is 
necessary  to  use  a  large  stereoscope  (Fig.  323). 

When  making  dental  stereoradiographs,  on  films 
Dental  film  held  in  the  month  during  their  exposure,  the  problem 

Bolder.  of  replacing  the  first  film,  after  its  exposure,  with  a 

second  film,  which  will  occupy  precisely  the  same 
position  as  the  first,  is  one  fraught  with  great  difficulties.  In  an  effort 
to  accomplish  this  the  writer  uses  a  Kny-Sheerer  film  holder  and  model- 
ing composition.  The  film  holder,  as  I  nse  it,  is  modified  almost  beyond 
recognition  (see  Figs.  331.  332  and  333).  Films  may  be  placed  in  this 
modified  holder  in  exactly  the  same  position,  and,  by  the  aid  of  the  im- 
pression of  the  occlusal  surfaces  of  the  teeth  in  modeling  composition, 
the  holder  may  be  replaced  in  the  mouth  in  the  same  position.  This  film 
holder  is  applicable  to  practically  any  part  of  the  mouth,  but  especially 
so  to  the  molar  region. 

It  is  not  absolutely  necessary,  but  I  prefer  to  have  the  patients  pose 
in  a  recumbent  position  for  all  dental  stereoscopic  work,  believing  they  are 
less  likely  to  move  the  head  while  the  films  are  being  changed  in  this 
position  than  they  would  be  if  sitting  in  a  chair.  Thus  the  pose  for 
making  Fig.  347  was  a  slight  modification  only  of  Fig.  330. 

Thanks  to  the  work  of  Dr.  C.  Edmund  Kells,  we  now  know  that  it 
is  not  necessary  to  have  the  two  films  in  exactly  the  same  position  to  make 
a  stereoradiograph  like  Fig.  348.  All  that  is  necessary  is  to  have  them 
occupy  exactly  the  same  plane.  Hence  no  film  holder  need  be  used.  The 
film  is  placed  in  the  mouth  as  in  Figs.  88  and  89. 

After  the  two  film  negatives  are   made,   prints 
Preparation  of         ma-v  De  ma^e  from  them,  and  these  prints  mounted  on 
Kadioqrapbs  for        cardboard  to  be  observed  with  the  hand  stereoscope. 
Study  with  Stereoscope.    (  )t  the  negatives  themselves  may  be  observed  stereo- 
Mr,  pir;dly   by    mounting   them   on   transparent  glass, 
Sticking  them  in  place  with  binding  strips  such  as  are  used  in  passe  par- 
tont  work. 

The  distance  between  the  radiographs  mounted  for  stereoscopic  ob- 

tion  should  1"-  approximately  two  and  one-half  inches  from  a  given 

point  it1  one  radiograph  t<>  the  same  poinl  in  the  other  radiograph.    Greal 


STEREOSl  OPIC   RADIOGRAPHY 


.V 


Fig.  345.     Anteroposterior  view  of  a  dry  skull.     The  right  sphenoid  sinus  is  filled  with  lead  shot. 

accuracy    in    mounting    the    radiographs    for    stereoscopic    study    is    not 
necessary  though  preferable. 

It    is    always    expedient    when    making    dental 
CandmarkS.  stereoradiographs  to  place  some  landmark,  such  as 

an  anchor  clamp  band'or  a  wire,  on  the  teeth.  Know- 
ing then  that  the  screw  and  nut  of  the  clamp  band  are  on  the  lingual  or 
buccal  side,  as  the  case  may  be,  or  that  the  wire  is  twisted  on  the  lingual 
or  labial  side,  as  the  case  might  be,  we  mav  determine  immediately,  when 


Fig.   346.     The   reproduction   here  has  lost   much   of  its   excellence.      When    the   original    negatives 

were   viewed  in  the  illuminating  stereoscope,  one  could  look  as  clearly   and  directly  into  the   skull 

as  he  could  into  a  soap  bubble.     The  dark  outline   is   the   antrum   nearer  the   observer  filled  with 

lead   shot.      (Stereoradiograph  by   A.   M.   Cole   and   Raper.) 


312 


DENTAL    RADIOGRAPHY 


observing  the  stereoradiograph,  whether  we  observe  the  part   from  the 
position  of  the  tube  or  the  position  of  the  film. 

Dr.  Kells  states  that,  as  a  general  proposition,  a  more  perfect  stereo- 
scopic effect  may  be  gained  if  the  radiographs  are  mounted  so  that  the 
stereoradiograph  is  observed  from  the  position  of  the  film.  This  is  true, 
and  one  reason  for  it  is  that,  other  things  being  equal,  the  closer  an  object 


Fig.    347.      Impacted   lower,   left,   third   molar,   viewed    from   the   lingual.      The   screw   and    nut   of 
the  clamp   band   are   on   the   lingual. 


Fig.    848.      Viewed    from  the  position   of  the   film — from   the   lingual.     The   temporary   cuspid    is 

so  much  decayed  and   resorbed   it    can    scarcely   be  seen.     The   win-  around   its   neck  can   Ite  seen 

clearly.       The    wire    is    twisted    on    the    labial. 

the  plate  or  film  the  clearer  n  is  outlined  in  the  radiograph.  Like- 
wise a-  we  look  Upon  a  -ceiie.  the  closer  objects  are  clearer  than  those  at 
a  distance.  Hence;  when  we  observe  a  stereoradiograph  from  the  position 
of  the  film  or  plate  during  its  exposure,  those  parts  of  the  stereoradio- 
graph seeming  to  la-  closer  to  us  are  clearer,  while  those  farther  away  are 
less  clear. 

If  the  film  packets  used  contain  two  films  each,  four  negatives  will 
]»'    mad'-,  and  these  may  be  mounted  on  clear  glass,  so  that  the  operator 


STEREOSCOPIC   RADIOGRAPHY 


3*3 


may  observe  the  part  from  the  position  of  the  film  and  tube  also. 

In  direct  proportion  as  tilings  are  large  or  small 
it  is  easy  or  difficult  to  discern  perspective.  The 
parts  in  dental  radiographs  are  so  small  that  it  is 
difficult  to  gain  perspective.  In  an  effort  to  over- 
come this  handicap,  to  an  extent  at  least,  Fig.  350 

was  made.    Fig.  350  is  an  enlargement  of  Fig.  349.    Owing  to  the  loss  of 


enlargement 

of  Dental 

Stereoradiography 


Fig.   34S'.     Impacted   upper,   third   molar,   viewed    from    the   position    of   the   tube.     The    wire    pass- 
ing  around   the    neck    of    the    second    molar    is    twisted    on    the    lingual.     The    impacted    tooth    sets 

to    the    buccal. 


Fig.    350.      Same    as     Fig.     349    enlarged. 

detail  incident  to  enlargment  there  seems  little   if  any   advantage   in    I 
step.     There  is  none  made  at  the  present  time,  but  a  magnifying  stereo- 
scope would  probably  be  of  value  for  viewing  dental  stereoradiographs. 

So  much  for  the  technic  involved  in  the  practice 

Practical  Ualue         °^  ^ental  stereoscopic  radiography.     Let  us  now  con- 

Of  Dental  Sterec-        sider   the   results,   the   practical   application   and    the 

radiographs.  possibilities     of     dental     stereoscopic     radiography. 

Frankly,   the   results  are  discouraging.      Considering 


3i< 


DENTAL   RADIOGRAPHY 


the  difficulties  of  practice,  and  the  results  obtained  at  the  present  time, 
there  is  an  extremely  limited  practical  application  of  the  stereoradiograph 
to  dentistry.  What  the  future  possibilities  of  dental  stereoscopic  radiog- 
raphy are  I  wi  uld  not  attempt  to  say.  My  hope  is  that  some  day  we 
may  be  able  to  stereoradiograph  the  upper  molar  roots  successfully. 

By  describing  i;  1  think  I  have  proven  that  the  technic  involved  to 
do  dental  stereoscopic  work  is  so  difficult  that  the  work  should  be  left 
entirely  to  specialits  in  radiography.  Even  in  the  hands  of  the  most 
skillful  it  seems,  at  the  present  time,  that  there  are  several  good  reasons 
why  it  will  never  he  popular.     The  reasons  are:     (  i  )  The  difficulty,  and 


—* 

"""*1 — 1 — T — "*  ~ 

* 

J 

-N— 

L  ... 

.  _     J     IT  .1 

!"" 

H 

,, 

■      el 

1.      Coins   at   flifTt.-n.-nt    distances    from    a    wire   screen. 


at  the  same  time  the  necessity,  of  obtaining  two  radiographs  uniformly 
rich  in  detail.  (2)  The  difficulty  and  necessity  of  placing  two  films  in 
the  mouth  in  the  same  position.  (  3)  The  difficulty  and  necessity  of  having 
the  patient  maintain  the  same  pose  while  the  two  exposures  are  made. 
(4)  The  great  amount  of  time  consumed  to  do  the  work.  (5)  The  parts 
g  so  -mall  makes  it  especially  difficult  to  gain  a  stereoscopic — a  per- 
spective— effect.  (6)  One  of  the  most  important  reasons  why  dental 
stereoscopic  work  probably  never  will  he  popular,  even  among  specialists, 
is  that  we  feel  no  great  need  of  it.  The  single  radiograph  is  not  totally 
lacking  in  perspective,  and  a  careful  study  of  it  will  reveal  almost,  if  not 
quite,  as  much  as  can  be  seen  in  the  dental  stereoradiograph.  (7)  The 
stereoradiograph  is  sometimes  misleading.  For  example,  witness  Fig.  351. 
To  make  this  illustration  three  coins  were  placed  on  a  piece  of  wire 
screening,  one  tlirectlv  against  the  screen,  the  other  two  resting  on  cotton 


STEREOSCOPIC   RADIOGRAPHY 


3 '  5 


built  up  to  hold  them  at  different  distances  from  the  screen.  In  the 
stereoradiograph  the  coin  which  rests  against  the  screen  seems  to  stand 
out  from  it  a  short  distance. 

Some  day  perhaps  we  may  so  modify  and  perfect  our  technic  that 
the  stereoradiograph  will  be  of  indispensable  value  (i)  in  observing  the 
three  roots  of  upper  molars;  (2)  in  seeing  a  wire  passing  through  a 
perforation  to  the  labial,  buccal  or  lingual;  (3)  in  some  particular  cases 


Fig.    352.      Same    as    Fig.    339    made    "plastic.' 


of  impacted  teeth  to  show  mure  exactly  their  location,  and  so  aid  in  the 
extraction;  (4)  in  showing  the  orthodontist  when  he  may  move  the  com- 
ing permanent  teeth  by  moving  the  deciduous  teeth;  (5)  in  determining 
more  exactly  than  can  be  done  with  the  single  radiograph  the  size  and 
location  of  a  pus  cavity  or  cyst;  (6)  in  cases  of  fracture  of  the  mandible; 
(7)  in  locating  exactly  bone  "whorls,"  calculi  in  the  glands  or  ducts  of 
glands  and  foreign  bodies  in  the  antrum;  (8)  in  learning  the  size,  shape 
and  location  of  the  antrum  as  an  aid  in  opening  into  it;  and  (9)  in  cases 
of  tumor  to  locate  more  definitely  the  offending  body. 


3*6 


DENTAL    RADIOGRAPHY 


Plastic  Radiography. 

There  is  no  one  thing  which  so  limits  the  usefulness  of  the  radio- 
graph as  its  lack  of  good  perspective.  Hence  our  interest  in  stereoscopic 
radiography.     Hence,  also,  our  interest  in  plastic  radiography. 

Plastic  radiography  is  a  method  of  making  radiographs  in  such  a 
way  that  the  parts  stand  out  in  has  relief.     A  better  name  than  plastic 


1 

^r 

Fig.   353.      Plastic   reproduction  of  Fig.    347. 


.1.      Fig.    353    enlarged. 


Cechnic  of 

Plastic 

Radioarapby. 


radiography  would  have  been  trick  radiography.     I  describe  the  method 
simply  as  a  matter  of  interest.     It  is  of  no  practical  value  whatever. 

The  following  are  the  steps  in  making  a  plastic 
radiograph.     The   negative   is   made  as  usual.      For 
convenience  in  referring  to  it  we  shall  call  the  nega- 
tive the  first  picture.     From  the  first  picture  another 
picture,  the  second  picture,  is  made  on  a  photographic 
plate,  the  technic   for  doing  this  being  the   same  as    for  making  lantern 
slides  (sec  Chap.  Y).    The  first  and  second  pictures  are  now  placed  to- 
ensitive  ^ides  in  appositii  n,  held  up  to  the  lighl  and  moved 
about  until  the  parts  of  the  two  pictures  overlie  one  another  exactly.    They 
now  held  immovable  while  an  a^sistanl   -ticks  them  together  with 


STEREOSCOPIC   RADIOGRAPHY  317 

paper  binding  strips.  Next,  place  them  in  a  printing  frame  and  make  a 
photographic  print  on  paper  (see  Figs.  335.  352,  353  and  354).  While 
the  exposure  is  being  made  the  printing  frame  must  remain  immobile 
and  the  light  must  pass  through  pictures  number  one  and  number  two  and 
strike  the  photographic  paper  at  an  angle  of  about  ninety  degrees. 

Instead  of  allowing  the  light  to  pass  through  pictures  one  and 
two  and  strike  the  photographic  paper  at  an  angle,  the  same  result 
may  be  accomplished  by  allowing  the  light  to  pass  straight  through  pic- 
tures one  and  two,  if  at  the  time  they  are  stuck  together  the  two  pictures 
are  almost,  but  not  quite,  in  perfect  overlying  opposition. 

Instead  of  making  the  print  on  paper  from  pictures  one  and  two, 
another  picture,  number  three,  may  be  made  on  a  plate,  and  from  this 
third  picture  photographic  prints  made  (Fig.  336). 

Plastic  radiography  is  simply  a  scheme  of  shading  radiographs 
Nothing  more  can  possibly  be  seen  in  the  plastic  production  than  could 
have  been  seen  in  the  original  negative,  though,  perhaps,  something  may 
be  seen  more  easily.  To  the  man  unacquainted  with  the  reading  of  radio- 
graphs the  plastic  pictures  seem  much  clearer,  but  to  the  man  of  experi- 
ence it  is  not  so  clear,  for  there  is  an  unavoidable  loss  of  detail  in  the 
making  of  the  plastic  reproduction. 

Figs.  352,  353  and  354  are  plastic  stereoradio- 

PlastiC  graphs.     It  is  interesting  to  pause  and  consider  the 

Stcrcoradiograpbs.       number  of  steps  necessary  to  make  Fig.  354.     First. 

the  negatives   were   made ;   from  these  the   "second 

picture"  of  the  plastic  method,  then  the  prints  on  photographic  paper, 

from  which  enlargements  were  made,  and  then  the  halftone. 

In  concluding  let  me  say  that  the  properly  made,  intelligently 
read  single  radiographic  negative  is  of  the  utmost  importance  and  value 
in  the  practice  of  dentistry.  Let  us  not  forget  this,  and  let  us  not  decrv 
the  radiograph  because  our  efforts  in  stereoscopic  and  plastic  work  fail  to 
make  it  absolutely  infallible. 


INDEX 


Abortion   277 

Abscess. 

Alveolar   185 

Dentoalveolar    185 

Destruction  of  Tissue  in 187 

Multirooted  Teeth 100 

Number  of   Teeth  [nvolved 189 

<  » f  Crowned  Teeth 191 

I  »pening  on   Cheek 253 

Pericemental  195 

Pyorrhea    Alveolaris,    Differential 

Diagnosis    193 

Absorption  of  Teeth  (See  Resorption) 

A.  C 2,  9,  11,  24,  295 

Acid   Fixing  Bath 78 

Alopecia  278 

Alternating  Current 2.  9,  11.  24,  295 

Alveolar    Abscess 185 

Ammeter  or  Amperemeter 32 

Ampere  4 

Amputation  of  Apex  of  Tooth  Root  201 

Angle  «'f  X-ray- 91  to  94 

Ancle  41,     -X2 

Ankylosis    247,  262 

Anomalies    230 

Anti-Cathode   41.     42 

Antrum  of  Highmore 234 

Foreign  Body  in 238 

Pus  in -'.^-I 

Radiographing  of [08,    114 

Apparatus,    Radiographic 294 

Apicoectomy  201 

Aprons,    X-ray    Proof _>X0 

Armature   9 

Arsenical    X'ecrosis 231 

Vrticulation,    Temporo-mandiliular. 

Artificial    Roots 213 

ant   Anode 44 

Azo  83,  104 

Baldness   278 

Bi-anodal  X-ray  Tubes ti 

Bismuth    Paste [<&,  264 

Blood    Supply 

Bone    •Whorl." 214 

Bridgework  209  to  21: 

Bromide  Paper 1 10.  1  [8 

Brol 

Broach   in   Canal 204,   20J 

I   Ootll      ...  205 

Burn.  X  I  >'  rmatitis  1 


Cabinet,   Protective  Lead 280,  283 

Calculus    200 

Canals  of  Teeth, 

Broach  in 204,  205 

Enlarging    176,  210 

Filling    175,  176 

Finding   172 

Cancer   274,  275 

Caries, 

Dental   269 

Of   Bone 231 

Cathode  41,    42 

Cathode    Stream 48,   49,     52 

Cementoma   214 

Circuit.    Electric 10 

Coil, 

High    Frequency    (See   High   Fre- 
quency Coil). 
Induction   (See  Induction  Coil). 
Interrupterless    (See    Interrupter- 
less  Coil ). 

Color  of  X-ray  Tube 51,     52 

Commutator    9 

Compression  Cones  and  Diaphragms, 

63,     64 

Condenser 34-35.     36 

Conductors,   Electric I 

Congenital   Absence   of  Teeth    (See 
Missing  Teeth  ). 

Converter,   Rotary 36,     ^7 

Crowned  Teeth 181,  191 

Currents  2,  38,     53 

CutOUtS    (  See     I'Uses  ). 

Cutting  of  Teeth,  Delayed 148 

Cvcle    2 

Cyst 

Bone    218 

Dentigerous  222 

I  (anger, 

I  If   Electric  <  Currents .^2,    38 

I  If  the  X  rays 273 

To  '  Operator 287 

To   Patient 288 

I  >ark    Room 67 

Dark   Room  Lantern 68 

I).    (' -'     <).     M.     10.    29S 

Death,  from  X-rays 275,276 

I  <>  •  iduous    I  eeth 157.  t6i,  162,  163 

Delayed  Eruption  of  Teeth 148 

Densities,   Recorded  on   Radiograph. 

136,  '38 


I  >enticles  250 

Dentoalveolar  Abscess [85 

Dental    Radiograph 1 .     85 

Dental  Stereoradiography 

Practical  Value  of 313 

Technic  for  Making 309 

Dermatitis    273,  274.  290 

Developer  74 

Choice   of 102 

I  [ydrochim  m   75 

M-Q  7-, 

I  emperature  76 

Development. 

Of  Negative 74.  102 

Of  Prints S3,  104 

Of   Teeth 264 

Destruction    of     Tissue,    Bone    and 
Tooth 187 

Diagram, 

Cathode   Stream 48 

Compression  Cone  and  Diaphragm,     64 

High  Frequency  Coil 36,  38,  129 

Induction  Coil 20,  32.  33,     34 

Mechanical    Interrupter 28 

Pose   for  Radiographs. ..  .70,  91  to  94 

Rheostat    31 

Shunt  45 

Stereoscopic  Work 301 

Switch   22 

Valve  Tube  in  Use 54 

X-rays   48 

X-ray  Tubes 46 

Diaphragms  and  Compression  Cones, 

61.  64,  301 

Differential  Diagnosis,  Pyorrhea  and 

Abscess   193 

Differentiation,     Primary    and     Sec- 
ondary Teeth 161 

Dislocation   of   Condyle 242 

Direct  Current 2,  9,  II.   19,  295 

Distance    Between   X-ray   Tube   and 

Patient    97 

Drying, 

Of   Negatives 80.   103.   104 

Of   Prints 84.   106 

Duration   of  Exposure 71,     99 

Dynamos    9 

Ear,  Pain  in 228 

Education  in  Radiographic  Work, 

292,  293 

Electricity    1 

Electrolyte    17,    21 

Electromagnets   7 

Elementary   Radiography 1  to  85 

Empyena    of    Maxillary    Sinus 23J 

Ethmoid    Cells 234,  J1,; 

Exposure, 

For   Prints 83,   104 

Of  Patient.  Time  Limit 2S8 

Time  of.  for  Negatives 71 . 

Exostosis,   Dental 214 


Extraction  of  T&eth u  ._- 

Eye,   Disturbance  of 172 

Facial  Neuralgia   I  Sec  Neuralgia). 

Faraday    8 

Fatality,  from  X-ray  Lesions. .  .275,  276 

IVrrotx  pe    106 

Field    9 

Filling, 

Canals    175,  176 

Encroaching  on   Pulp iN: 

Large  181 

Film, 

I  )escription  of 66 

1 1<  ilder   98,  304.  310 

Methods      of      Holding      in      the 

Mouth   98,  304.  310 

Placing  Outside  the  Mouth 106 

Position  of  and  Direction  of  Ravs,  90 

Protection  of 86.  87,  98 

Radiographs,  Advantages  of 114 

Special    X-ray 66,  85 

Filter   289 

Fistula  on  Face 253 

Fistulous  Tract 199 

Fixing, 

Box    79 

Of  Negatives 77.  104 

Of    Prints 84 

Fluoroscope 55,  56,  143,  144 

Foreign    Bodies 202 

In  Antrum 238 

Fracture, 

Of  Tooth 208 

Of   Jaw 244 

Friedlander's   Shield 63.  64 

Frontal  Sinuses 234,  235.  237 

Fuses 17.  21 

Generator  9 

Grounding  the  Current 1 T2 

Gloves    286 

Hair,  Loss  of 278 

Headache  260 

High  Frequency  Coil. 

Description   of 33 

Diagram   of 36,  38.   129 

Radiographs   Made  With...  124  to  130 

Technic  Involved  in  Use  of 130 

Hydrometer  21 

Hypercementosis   (See  Cementoma). 

"Hypo"   78.   79.  261 

Hypochondriac   261 

Idiopathic   Neuralgia 2^2 

Illuminating    Boxes 136.  298 

1  mmunity    290 

Impacted  Teeth 168,  256,  262 

Induction   Coil, 

Description    of T5 

Diagrams  of 20.  32.  33.  34 


Radiographs   .Made   With, 

73,   [20  to  124,  and  133  to  135 

rechriic  Involved  in  Use  of 88 

Interior    Dental    Canal 252 

Inflammation  About  Bridge 211 

I  nsanity   256,  277 

Insomnia    256 

Installation   15,  36 

Insulation   7,  27 

Intensifier 81 

Intensifying    Screens 101 

Interrupterless  Coil, 

Description  of 39 

Radiograph  Made  With 132 

Technic  Involved  in  Use  of 88 

Interrupters 17  to  25 

Inverse   Current 53 

Jumping  the   Bite 263 

Kilowatt    5 

Kilowatt-hour   5 

l\  resku    I0_| 

I  ame    Teeth 184 

Lantern  Slides Ii8 

Lassitude   278 

Lead    Cabinet 280 

Lead   Screen 280,  295 

Leukemia    277 

Life.    Loss   of 275,  276 

Locked  Jaw 262 

Ludwig's   Angina 253 

Luxatii  m    242 

Magnetism   5 

Magneto   9 

Making  Photographic  Prints 83,  104 

Making  Negatives  (See  Negatives). 

Making  Radiographs 65,  85 

Malformed    Teeth -'30 

Marking   Negatives 141 

Maxillary  Sinus    (See  Antrum). 

Maxillary    Suture »66 

Meters  32 

Methods    of    Holding    Film    in    the 

Mouth 98,  304 

Missing   First    Molar 153 

Missing  Second   Molars 155 

Missing     First,     Second     and      Third 

Molars     155 

Missing  Teeth [48,   157.  266 

Motor    37 

Moisture,   Protection  of  Film  from. 

86.    87 
Myelosarcoma  of  tin-  Lower  Jaw...  226 

\'  1  ro^is    23] 

Negatives  78,  137,  141 

l  'evelopmenl   of 7.4.  to  ■ 

I >r-, ing  of 80.   103.  ioj 

Faults    in 81.  82 


Fixing   of 77,  104 

Intensification  of 81 

Marking  of 141 

Reducing  of Si 

The    Relative    Values    of    Dense 

Areas    in 136,   138 

Washing  of 79,   104 

Neuralgia,  Facial 249,  also  160,  180 

Neurasthenia 256 

Neuroses    256 

Nonconductor   1 

North  Pole  of  Magnet 6 

Odontoma   151,  228,  229 

Ohm 3 

Ondoscope    or    Oscilloscope     (Same 
as  Oscillimeter). 

Oscillimeter   54 

Osteology  263 

Osteoma  227 

Pain,  of  X-ray  Lesions 277 

Paper,    Photographic 83,  104 

Penetration  of  X-rays 56 

Penetrometer    55 

Perforation  of  Teeth 179 

Pericemental    Abscess 195 

Pericementitis,   Chronic 184 

Perspective   142,   144,  297 

Photographic  Paraphernalia  Needed  294 

Placing  Film  Outside  the  Mouth 106 

Planted    Teeth 212 

Plastic  Radiography 316 

Plastic   Stereoradiography 317 

Plate    Changers 299 

Plates  and  Films, 

Photographic 65 

X-ray    66 

Pose  for  Making  Radiographs. 

Of  the  Upper  Anterior    Teeth....  96 

Of  the  Antra  of    I  lighmore.  .  .  108,  114 

Of  tlie  Lower  Anterior  Teeth. 100,  108 
Of  the  Lower  Anterior    Teeth  and 

Antra 108 

Of  the  Lower  Molar  and  Bicuspid 

Region     99 

Of  the  Upper  Molar  and  Bicuspid 

Region    92 

With  the  Film  Outside  the  Mouth  107 
Pose  for  Making  Stereoscopic  Men- 
tal Radiographs  303 

Position  of   Film  and    Direction  of 

X   rays   90 

Position   of    Film   in   the   Month. 

89,  95,  97 

Positive    Wire,     lest    for 19 

Positives    83 

Potential    2,  3 

I  'regnancy   277 

Primary. 

Current    II,   12,  27,  33 

'I  eeth   (  See  I  deciduous  Teeth). 
Winding  11.  12.  27,    33 


111 


Prints,  Photographic >37.  '3s 

1  kvelopment   of °3 

Drying  of 84,  106 

Exposure  83,  in4 

Fixing  of • °4 

Toning  of io5 

Washing   of °4 

Probing IO| 

Protection    278 

Apron    286 

Cabinets    280 

Gloves   280 

Of  Films 86,  87,  98 

Screens    280.  205 

Shield  59  to  63.  285 

Spectacles  286 

X-ray   Tube 285 

Psych'  ises   25° 

Pulp   Nodules,  or  Stones 179 

Punctured  X-ray  Tube 52 

Purchasing  a  Radiographic  Outfit...  292 

Pyorrhea    Alveolaris 193.  293 

"Pyro"    /"o 

Radiographic  Outfit,  Purchasing  a..   292 

Radiograph  or  Radiogram 63 

Radiographs  Made  Direct  on  Photo- 
graphic Paper 1 1 6 

Radiographs.     Preparation     of.     for 

Study  with   Stereoscope 3In 

Radiography. 

Elementary    1   to  85 

Dental   85  to  317 

Plastic   3i6 

Stereoscopic    i-l-l-  297 

Radium  Rays 291 

Reading    Radiographs 136 

Records, 

Of  Densities  in  Radiographs.  .  136,  138 

Radiographic    Records 268 

Rectifier    24 

Reducer    81 

Reproductions  l37 

Requirements     of     a     Radiographic 

Outfit   294 

Research    Work 263 

Resorption  of   Teeth. 

157.  165,  168,  169,  213.  266 
Resection. 

Of  Inferior  Dental  Nerve 252 

Of   Mandible 247 

Retained   Deciduous   Teeth 157 

Rigg's    Disease    (See    Pyorrhea   Al- 
veolaris ). 

Rheostat    25 

Rodinal    103 

Roentgen    65 

Rav  (  See  X-ray ) . 

Win.    Condar 49 

Roots  of  Teeth, 

Absorption  of   (See  Resorption). 
Artificial     -'3 


Amputation    oi 201 

Fracture  of 208 

F(  inning    160 

Fusion  of 203 

In    Antrum 238 

Radiographed   for  Bridgework 209 

Rotary  Converter 36 

Ruhmkorff  Coil   (See  Induction  Coil). 


Sen  mdary, 

Current II,    12,  27. 

Dentin   

Rays    '. 57' 

Winding II,   12,  27, 

Shield,  for  X-ray  Tube  (See  Pro- 
tection Shield). 

Shunt    

Short    Circuit 

Skiagraph,  or   Skiagram 

Solio    

South  Pole  of  Magnet 

Spark  Gap,  Terminal. 

20,  28,  35,  36.  40,  43. 

Current  or  Coil  Regulating 35- 

Inverse  51, 

Parallel   (Same  as  Terminal). 

Series    52- 

lube    Regulating 4<->. 

Spasm,  Facial   Muscles 

Specialists  in   Radiographic  Work.. 

Spectacles    

Sphenoid    Cells 

Sqeegee   Board 

Stands,  X-ray  Tube 59.  60,  284. 

Static   Machine 

Stereoradiography. 

Technic   for   Making 

Plastic   

Stereoscope    297. 

Stereoscopic, 

Radiographv    H4 

Table   

Tube    Stand 

Sterility    

Stones, 

Pulp   

Salivary    

Supernumerary    Teeth 

Suppuration  168,  196  (See  Abscess 
and  Pyorrhea). 

Switches    


Technic, 

For   Covering   Films 86 

For  Making  Dental  Radiographs..  85 
For  Making  Plastic  Radiographs.   316 

For   Making   Radiographs 65 

For  Making  Stereoradiographs. .  .  297 
For  Using  a  High-Frequency  Coil  130 
For  Using  an  Induction  Coil.....  88 
For  Using  an  Interrupterless  Coil.     88 


33 

180 

289 

33 


4-' 

Ml 

65 

104 
6 

44 
36 
53 

53 

47 

260 

292 

286 

3ii 
106 

295 
14 

297 
317 
298 

297 
300 

303 
277 

179 

217 

107 


IV 


Teeth, 

Abscess  of  (See  Abscess). 

Absorption  of  (See  Resorption). 

Caries  of,   Hidden 

Canals  of   I  Sec  Canals  ). 

Crowned    181. 

Cutting,    Delayed 

Deciduous 157.   [61,  162, 

Delayed   Eruption 

1  Jevelopment  of 

Differentiation    Between    Primary 
and    Secondary 

Enlarging  Canals  of 176, 

Eruption   of.   Delayed 

Extraction    of 162, 

Filling   (  See  Filling). 

For    Bridgework 

Forming  Roots  of 

Fracture    

Impacted    168,  256, 

Lame    

Malformed    

Missing    148,    157, 

Moving    163. 

Planted    

Primary    (See  Deciduous). 

Resorption  of, 

157,  165,  168,  169,  213. 

Retained   Deciduous  Teeth 

Roots  of   (See  Roots). 

Supernumerary    

Tumor    of 

Temporary    Teeth    (See    Deciduous 

Teeth). 
Temporo-mandibular   Articulation, 

242, 
Tesla    Coil     (See     High-Frequency 
Coil). 

For   Polarity  of   Induction  Coil... 
For    Polarity   of    Lead   Wires   on 

D.    C 

Therapeutic  Agent,  X-rays  as 

Tic  Douloureux  (See  Neuralgia). 

'I  i<\    Facial   Gesticulatory 

Titubator    

Toning    

Transformer,    11     (Sec    also    Inter- 
rupt rless  <  oil  i. 

I  ra>  rocker    

for  Developing  and  Fixing, 
7  1- 
Trigeminal  Neuralgia  (Sec  Neural 
gia). 

I  ube,    Valve 

Tube,    X-ray 

And  Patienl    I  Kstance  Bel  Ween..  . 

Bi-anodal    

Color   of 51. 



Hard     

High    


269 

191 
148 
163 
148 
264 

161 
210 
148 
168 

209 
160 
208 
262 
184 
230 
266 
164 
212 


266 

i57 

167 
214 


266 


41 

ig 
293 

260 
78 


Ki.; 


54 

41 
<>7 
44 
52 
•1' 
42 
42 


High-Frequency   57.    58 

Inverse    in 52,     53 

Low    42 

Properly    Lighted 50 

Puncture   of 52 

Rack    58 

Shield    59    to   63,  285 

Soft    42 

Stand 59,  60,  284,  295 

Vacuum    41,    42 

Vacuum    Regulator 45 

Target    41,     42 

Tumor 151,  214,  224  to  229,  250 

Turbinate    Hones    2/^ 

Twitching    260 

Uses    of    the    Radiograph    in    Den- 
tistry        146 

(\)  In  Cases  of  Delayed  Erup- 
tion to  Determine  the  Pres- 
ence or  Absence  of  the 
Unerupted  Teeth 148 

(2)  In    Cases    Where    Deciduous 

Teeth  are  Retained  Long 
After  the  Time  When  They 
Should  Have  Been  Shed,  to 
Learn  if  the  Succedaneous 
Teeth  be  Present 157 

(3)  To    Learn    if    the    Roots   of 

Children's  Teeth  are  Fully 
Formed  160 

(4)  To     Determine     Whether     a 

Tooth  be  One  of  the  Pri- 
mary or  Secondary  Set....    161 

(5)  To  Determine  When  to  Ex- 

tract Temporary  Teeth 162 

(0)  To  Show  the  Orthodontist 
When  lie  May  Move  the 
Coming  Permanent  Teeth 
by  Moving  the  Deciduous 
Teeth   163 

(7)  To  Observe   Moving  Teeth..    164 

(8)  In  Cases  of  Supernumerary 
Teeth    167 

(o)    In  Cases  of   Impacted  Teeth 

as  an  Aid  in  Extraction....    168 

(10)  To    Determine   the    Number 

of  Canals  in  Some  Teeth...    172 

(ii)  As  an  Aid  in  Filling  the 
Canals  of  Teeth  with  Large 
Apical    Foramina 175 

(12)  To  Learn  it'  Canals  Are 
1  Ipeh  and  Enlarged  to  the 
\prx  Before  Filling  and  to 
<  Ibserve    tin     (  anal    Filling 

\  ftcr   the   (  >p<  ration 176 

1  1  1 1  I  1 .  I  letermine  Whether  an 
( opening  I  .eading  from  a 
Pulp  1  Shamber   Be  a  Canal 

or    a    I  'erf oration 170 

1  1  I  1    hi     ( '.iMs     of      Pulp     Stones 

(  Nodules  1   i79 


(15)  In  Cases  of  Secondary  Den-  (31) 
tin     Being     Deposited     and 

1 'inching  the   Pulp j8o 

(16)  To    Learn    if   the    Filling    in 

the  Crown  of  a  Tooth  En- 
croaches on  the  Pulp 181 

(17)  In     Cases     of     Teeth     with  (32) 
Large     Metal      hillings     or 

Shell     Crowns     Which     Do 

Not    Respond    to    the    Cold 

Test,  to  Learn  if  the  Canals  (33) 

Are  Filled 181 

(18)  To    Learn    if    Apical    Sensi-  (34) 

tiveness  is  Due  to  a  Large 
Apical  Foramen  or  an  Un- 
r  e  m  0  v  e  d  ,  UJndevitalized 
Remnant  of   Pulp 183  (35) 

(19)  In  Cases  of  Chronic  Perice- 

mentitis   (Lame  Tooth)....    184 

(20)  In    Cases    of    Alveolar    Ab-  (36) 

scess  to  Determine  White 
Tooth  is  Responsible  for 
the  Abscess 185  (37) 

(21)  In    Cases    of    Alveolar    Ab- 

scess to  Determine  the  Ex-  (38) 

tent   of   the   Destruction    of  (39) 

Tissue — Bony  and  Tooth...    187  (40) 

{22)   In    Cases    of    Alveolar    Ab-  (41) 

scess  to  Learn  How  Many 
Teeth  are  Involved 189 

(23)  In     Cases     of     Abscess     of  (42) 

Multirooted   Teeth  ;    to  (43) 

Learn  at  the  Apex  of 
Which     Root     the     Abscess  (44) 

Exists    190 

(24)  In    Cases    of    Abscesses    of  (45) 

Crowned  Teeth  to  Learn  if 
the  Canals  Are  Properly 
Filled    tqi 

(25)  As    an    Aid    in    Differential  (46) 

Diagnosis  Between  Chronic 
Alveolar  Abscess  and 
Pyorrhea  Alveolaris 193 

(26)  To   Observe   Destruction    of  '47) 

Tissue  Due  to  Pyorrhea  Al- 
veolaris      193  (48) 

(27)  In     Cases     of     Pericemental 
Abscess   195 

(28)  In  Cases  of   Persistent   Sup-  (49) 

puration  Which  Do  Not 
Yield  to  the  Usual  Treat- 
ment. (In  fact,  in  all  cases  (50) 
that  do  not  yield  promptly 
to  the  usual  course  of  treat- 
ment.)        196  (51) 

(29)  To    Observe    the    Course    of 

the   Fistulous  Tract 199  (52) 

(30)  To    Observe    the    Field    of 

Operation  Before  and  After 
Apicoectomy  (Root  Ampu- 
tation)       201 


To  Locate  Foreign  Bodies. 
Such  as  a  Broach  in  the 
Pulp  Canal  or  Tissue  at  tin- 
Apex  of  a  Tooth;  a  J'iece 
of  Wooden  Toothpick  in 
Peridental  .Membrane,  etc..  202 
To  Determine  the  Presence 
or  Absence  of  a  Bit  of  Root 
Imbedded    in    the    Gum 

Tissue    205 

To   Diagnose   Fracture   of   a 

Root  208 

To  Observe  the  Size  and 
Shape  of  Roots  of  Teeth  to 
be     Used     in     Crown     and 

Bridgework   209 

As  an  Aid  and  Safeguard 
when   Enlarging  Canals   for 

Posts   210 

To  Examine  Bridges  About 
Which  There  Is  An  Inflam- 
mation      211 

To  Observe  the  Field  Be- 
fore Constructing  a  Bridge.  212 
To  Observe  Planted  Teeth..  212 
In  Cases  of  Cementoma.  .  .  .  214 
In  cases  of  Bone  "Whorls".  214 
To  Locate  Stones  (  Calculi ) 
in    the    Salivary    Ducts    or 

Glands 217 

In  Cases  of  Bone  Cysts....   218 
In     Cases     of     Dentigerous 

Cysts    ■ 222 

In   Cases  of  Tumor,   Benign 

or    Malignant 224 

To  Observe  A  n  o  m  a  1  0  u  s 
Conditions,  Such  as  the 
Fusion  of  the  Roots  of   Two 

Teeth  for  Example 230 

To  Observe  the  Location 
and  Extent  of  a  Necroctic 
or     Carious     Condition     of 

Bone 231 

To  Diagnose  Antral  Em- 
pyema       234 

To  Observe  Size,  Shape  and 
Location  of  the  Antrum,  as 
an  Aid  in  Opening  Into  It. .  234 
To  Locate  Foreign  Bodies. 
Such  as  Tooth  Roots  or 
Broaches,  in  the  Antrum...  238 
To  Observe  Cases  of  Luxa- 
tion Before  and  After  Re- 
duction       242 

In  Cases  of  Fracture  of  the 

Jaw 24  1 

In  Cases  of  Ankylosis  of  the 
Temporo-  Mandibular  Arti- 
c  u  1  a  t  i  o  n  or  the  Joint 
Formed  by  the  Tooth  in  the 
Jaw 247 


VI 


I 53  >  To  (  (bserve  the  Field  of 
Operation  Before  and  After 
Resect  inn  of  the   Mandible.   247 

(54)  In  All  Cases  of  Facial  Neu- 

ralgia with  an  Obscure 
Ftiology    249 

(55)  To  Observe  the  Inferior 
Dental  Canal 252 

(56)  In  Ca^e^  of  Lndwig's  An- 
gina    253 

1  57  )  In  Cases  of  Insomnia. 
Neurasthenia,  Insanity  and 
K  in  d  red  Nervous  Disor- 
ders       256 

(58)  In  Cases  of  Periodic  Head- 
aches      260 

(59)  In  Cases  of  Facial  Gesticu- 
latory  Tic  (Spasmodic 
Twitching  of  a  Set  of  the 
Facial    Muscles 260 

(60)  To  Allay  the  Fears  of  Hy- 
pochondriac     261 

(61)  In  Cases  Where  the  Patient 

Cannot  Open  the  Mouth 
Wide  Enough  for  an  Ocu- 
lar  Examination 262 

(62)  In  Research  Work  to  Study 
Osteology,  the  Development 
of  the  Teeth,  the  Action  of 
Bismuth  Paste,  Bone  Pro- 
duction and  Destruction, 
Changes  Occuring  in  the 
Temporo-Mandibular  Arti- 
culation When  Jumping  the 
Bite,  Blood  Supply  to  Parts, 


Resorption     of     Teeth     and 

the   Causes   for  It,  etc 263 

(63)  As  a  Record  of  Work  Done  26S 
104)    In   Cases  of    Hidden   Dental 

Canes    269 

Vacuum    41.  45.  54 

Valve   Tube 54 

Velocitv  of  Electricity 3 

Velox 83 

Vibrator    17,  23 

Villard  Tube 54 

Volt   3 

Washing, 

Of  Negative 79.  i°4 

Of  Print 84 

Watt    5 

Winding, 

Primary 11,  12,  27,  33 

Secondary 11,  12.  27.  33 

Wiring  for  Installation 15,  36 

Wires    in    Canals 

173.    174,    175.    176.    179.  183 

X-ray   48.  49 

As   a  Therapeutic   Agent 293 

Burn    273.  274,  190 

Dangers   of 273 

Discovery   of 49 

Machines    14 

Outfit   294 

Penetration  of 5° 

Proof  Box 98,  101 

Tubes,  41   (See  Tubes). 

Tube  Stand 59.  60.  284,  295 


Date 

!  Due 

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